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Full text of "Bulletin of the British Museum (Natural History), Mineralogy"

THE NATURALLY OCCURRING 
CHROMATES OF LEAD 



S. A. WILLIAMS 



BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
MINERALOGY Vol. 2 No. 8 

LONDON: 1974 



THE NATURALLY OCCURRING 
CHROMATES OF LEAD 



BY 

SIDNEY ARTHUR WILLIAMS 

Phelps Dodge Corporation 
Douglas, Arizona 



Pp. 377-419 ; 7 Text-figures 



BULLETIN OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 
MINERALOGY Vol. 2 No. 8 

LONDON: 1974 



THE BULLETIN OF THE BRITISH MUSEUM 

(natural history), instituted in 1949, is 
issued in five series corresponding to the Departments 
of the Museum, and an Historical series. 

Parts will appear at irregular intervals as they 
become ready. Volumes will contain about three or 
four hundred pages, and will not necessarily be 
completed within one calendar year. 

In 1965 a separate supplementary series of longer 
papers was instituted, numbered serially for each 
Department. 

This paper is Vol. 2, No. 8, of the Mineralogical 
series. The abbreviated titles of periodicals cited 
follow those of the World List of Scientific Periodicals. 



World List abbreviation : 
Bull. Br. Mtis. nat. Hist. (Miner.) 



Trustees of the British Museum (Natural History), 1974 



TRUSTEES OF 
THE BRITISH MUSEUM (NATURAL HISTORY) 

Issued 25 September, 1974 Price £1.95 



THE NATURALLY OCCURRING 
CHROMATES OF LEAD 

By S. A. WILLIAMS 



DISCOVERY OF CHROMIUM 



CONTENTS 

Introduction 

Acknowledgements 

The historical background to the 

Crocoite .... 

Vanadium mistakenly identified as chromium 

Later observations on crocoite 

Vauquelinite 

Phoenicochroite 

Syntheses - real or supposed - of 

BASIC lead CHROMATES 

fornacite .... 

Embreyite .... 

Iranite and hemihedrite 
Santanaite .... 

Some doubtful species (jossaite, eosite, 4Pb0.3Cr03, beresovite 
bellite) ....... 

A summary of the valid and doubtful species 
Summarized data for the several species 
Select bibliography ..... 



phoenicochroite and of other 



Page 

379 
380 
380 
381 
386 

387 
390 
392 

395 
397 
397 
398 
398 

399 
401 

403 
410 



SYNOPSIS 

The history of the natural lead chromates is traced from 1766 to 1972, and the published 
physical and chemical data for the several valid species are summarized. A select bibliography 
of the primary literature on these minerals is appended. 



INTRODUCTION 

In 1971, during work in the Mineral Department of the British Museum (Natural 
History) on the nevi^ mineral embreyite, I became aware that this mineral had been 
observed at least once before, perhaps as early as 1789, but not recognized as a 
distinct species. At the suggestion of Mr P. G. Embrey, I embarked on a historical 
study that eventually included all the known natural chromates of lead. 

I have attempted to report all of the older works. Literature became voluminous 
in the last hundred years, and for this period I have tried to select only the more 
important papers. The original author's data have been quoted directly in most 
cases but in a few I have translated it into modern terms. Very old chemical 
analyses raise particular problems and if the author did not give weights obtained 
at every step of his procedure, but gave only final results, it was not possible to 
correct results using modern atomic weights. The literature is cluttered with 



38o THE NATURALLY OCCURRING 

misquotes, misprints and other errors. I have tried to set the record straight 
whenever possible. 

The study was made more thorough by free access to the Museum's large collection 
of specimens from Berezov ; the material from this locality was greatly augmented 
by the acquisition of N. Koksharov's collection in 1865. Examination of these 
materials has made it easier for me to visualize what has been described in the past 
and to judge the nature of the material studied and the quality of work accomplished 
by my predecessors. 

ACKNOWLEDGEMENTS 

This study would not have been possible without access to the superb library at the 
British Museum (Natural History). Most references were easily found ; Mr R. T. W. 
Atkins and Miss Julia Brown of the library of the Department of Mineralogy assisted 
me in finding the more obscure ones. If any early references have been missed I 
must accept the blame. 

Miss Eva Fejer has helped me immeasurably by translating Russian in several 
instances. Dr Pierre Bariand generously placed the type iranite specimen, and most 
of his collections from Iran, at my disposal. Dr Max Hey read the manuscript with 
great care and also checked many of the Russian locaUty names. The quality of 
this paper has been greatly enhanced by his efforts. My thanks are especially due 
to Mr P. G. Embrey, not only for suggesting the study, but for helpful discussion. 



THE HISTORICAL BACKGROUND TO THE DISCOVERY OF CHROMIUM 

Lead chromate minerals were first discovered in the Berezov mines in the central 
Urals. Earty travellers in Russia provide our first scraps of information. Marco 
Polo, when passing through Russia, south of the Ural Mountains, was told that there 
was much silver in Russia and that there were silver mines to the north. This was 
in about 1250 (Yule, 1921). Almost a century later Ibn Batuta also reported silver 
mines to the north when he travelled in the same regions as Marco Polo (Humboldt, 
1843). These reports are puzzling, because although a good deal of gold was later 
discovered in the Urals, gold carrying six to eight per cent silver, I have seen no 
mention in later writings of ancient silver mines in the Urals. 

The central and north Ural Mountains were sparsely settled and, except for 
hearsay reports from travellers such as Marco Polo and Ibn Batuta, were virtually 
unknown territory until, in 1723, Peter the Great laid the foundations of a town on the 
Iset River in the central Urals. The location of this community was chosen to guard 
the pass over the Urals and serve as an outpost for further expansion of the empire. 
The city was completed in 1726 (Cottrell, 1842) in the reign of Catherine I, and was 
named Ekaterinburg in her honour.^ Ekaterinburg immediately became a centre 
for the copper mining industry, which had begun in 1701 and was controlled by the 
Demidoffs. Nearly all its inhabitants were either government officals or associated 

1 EKaxepHHGypn, 56°52' N, 6o°35'E; it is now called Sverdlovsk (CBcpfljiOBCK) . Where possible, 
Russian localities are cited first in the author's spelling, then in the Cyrillic, and finally in modem 
English transliteration. 



CHROMATES OF LEAD 381 

with mining. When J. G. Gmehn (1751) visited Ekaterinburg in 1733-34 it had a 
hospital and one wooden church. He made a trip to the copper works, about 52 
versts away.i 

Prospectors were soon to find the gold mines near Berezov^ from which would come 
the first known lead chromates, but this had not happened before 1733-34, or surel}^ 
Gmelin would have mentioned gold mines so close to Ekaterinburg where he was 
staying, particularly since he had a more than ordinary interest in mining. Reports 
of other, later visitors, particularly Peter Pallas, all tend to confirm that gold mining 
began after Gmelin's visit. When Pallas visited Ekaterinburg in 1770 it had grown 
considerably. There were two companies of soldiers and an artillery detachment 
quartered there, and there were stone churches and even a jail. 



CROCOITE 

Some time between 1739 and 1766, in the gold mines near Berezov, the lovely 
orange mineral that is now called crocoite was found. It is strange that it was not 
reported until 1766, for it is strikingly beautiful and would immediately have 
aroused curio.sity. The first report of its existence is probably that of J. G. Lehmann, 
who announced his discovery in a letter (in Latin) to Comte de Buffon on the 2 July, 
1766. It is not certain that this letter was published. Dana (1951) cites : 'Nova 
minera plumbi (Lehmann, Nov. Comm. Ac. Petropol. 1766)', but there is no such 
paper in Novi Comment. Acad. Set. Imp. Petropol, 1766, vol. 10 (for 1764), in vol. 11 
(1767, for 1765), in vol. 12 (1768, for 1766 and 1767), or in vol. 13 (1769, for 1768). 

However, a German translation of the letter by Schulze appeared in 1767, and 
another independent German version in 1770 (Lehmann, 1767, 1770). In the 1767 
version the title of the letter is quoted : de nova minerae plumbi specie crystallina 
rubra ; and in 1769 B. G. Sage published a French version, using the name plomb 
rouge. 

Lehmann stated that the new mineral had been discovered at a mine 'Pirosowka 
Sawod', 15 versts from Ekaterinburg,^ and that the mineral had been mined with 
ores of copper, lead and silver. It occurred in cavities and interstices in quartz veins 
with altered pyrite and brilliant dendrites of a mineral resembUng hematite. It 
might adhere to quartz, to iron or copper minerals, or even to galena. The form was 
lamellar or crystalline with a spathic texture. Crystals were four-sided. The colour 
was given as bright yellow-orange with a saffron streak. But crystals broken open 
might be the colour of Japanese cinnabar within.* Finally he mentioned its 
association with 'plomb blanche' (cerussite) and 'plomb verte' (pyromorphite). 

Lehmann's chemical tests led him to believe that 'notre mine de plomb contient 
un spath seleniteux et du fer'. He looked for, but failed to find, sulphur, arsenic, 
cobalt, antimony, gold or silver. His analysis is incomplete, returning only 53-9% 

1 According to Kupffer (1833), a verst is 0-66288 miles; 1066-78075 metres. 

^ BepesoB (or BepesoBCKHH, Berezovskii) ; 57°o' N, 6o°5o'E; commonly misspelt 'Beresov'. There 
are now several towns with similar or identical names in various parts of the U.S.S.R. 

' The oldest mines in the Berezov district, eight versts from Berezov on the Pyshma River, would 
have been 15 versts from Ekaterinburg. 

* Such crystals could not have been crocoite : they were probably phoenicochroite. 



382 THE NATURALLY OCCURRING 

Pb. Exactly what Lehmann meant by 'spath seleniteux' is not clear. He may have 
considered it a sulphate; his test had shown only the absence of sulphide. No 
reference to selenium (discovered by Berzelius in 1817) can have been intended. 

Lehmann checked the literature to see if others had previously found an orange or 
red lead mineral. '^ The ancients are in accord - they knew of no such mineral 
although they were familiar with artificial red lead oxides. Lazarus Ercker (1580, 
1672 ; see also J. Pettus, 1683, and J. Justi, 1757) makes first mention of a red lead 
ore but said that it was clayey. J. G. Wallerius (1763) described a red lead ore as 
one stained with iron ochres. ^ M. V. Lomonosov (1763) mentioned bar-shaped or 
tabular red lead (with no silver content), but only in passing, and no locality was 
given. I find it hard to credit him with the discovery of crocoite as Hintze (1930) 
and Dana (1951) have done,^ for surely he would have given more information on 
such an unusual new mineral. Dana credits him with giving Berezov as a locality 
but I have been unable to find mention of this. To add further doubt to these 
claims, Lomonosov said his red lead mineral occurred on fluorite gangue, a mineral 
I have not seen in suites of Berezov material, and which has not been noted by other 
authors. 

P. Pallas, on his 1770 visit (Pallas, 1773 and 1794), is particularly helpful in the 
matter of date of discovery of crocoite. He visited the area near Totschilnaia- 
Gora,* where there was a sandstone quarry^ that had passed into control of the 
Demidoffs in 1739. At several quarries in the vicinity, such as the Kouschvinskoi, 
he found crocoite^ and at one he found 'fort belle mine de plomb blanc'. Pallas 
was also the first traveller to visit Berezov after Lehmann's announcement, and he 
paid attention to the mineralogy of the district. Although he saw specimens of the 
red lead ore from the mines he did not collect any. L Lepechin (1775) also was a 
visitor in the summer of 1770 but had little interest in mineralogy.' 

Pallas said that the gold mines were between the river at Berezov and the Pischma 
( = Pyshma) River, and were scattered over an area from one to eight versts from 
Berezov. The mines were near the village of Berezov and the Pyshma, Iset,^ 
Neiva and Taguil ( = Tagil) Rivers. There was yet another mine, 15 to 20 versts from 
Berezov on the Stanofka^ River ; it had produced gold from quartz veins like those 
at Berezov but they were lean and soon abandoned. The mines near the Pyshma 
were the oldest, dating back to 1745. The first of these was opened by eight shafts, 

"■ Lehmann, incidentally, mentioned only white and green lead ores in his text of 1756. 

^ In his 1778 edition, he described Lehmann's mineral plumbi rubra, and clearly did not consider it 
the same as the ochre-stained red lead ores of the earlier edition. 

^ Hintze writes: 'Die erste Erwahnung des Rotbleierzes findet sich bei Lomonossow (Grundlagen der 
Metallurgie, 1763, S. 44)'. The locality is not mentioned. Dana writes; 'Red lead-ore from Beresov. 
Lomonosov [Grundlagen der Metallurgie, 1, 44, 1763)'. 'Red lead-ore' is obviously a translation, but of 
what? Lehmann was either unaware of this mention or regarded it as another of the iron-stained ores 
mentioned by earlier authors. 

* ToiHjibHaa Fopa, Tochil'naya Gora (the village of ToHHjmaa Kjik)4, Tochil'naya Klyuch, 57°29' N, 
6i°i8' E, is 45 versts from Ekaterinburg). 

^ Pallas noted that some of these quarries had been worked centuries before. 

^ '. . . entre les fentes etroites de la pierre, beaucoup de cristaux plats de mine de plomb rouge. ..." 
He said the crystals were not very large, only up to an inch and a half long(!). 

' He gives, however, an interesting account of the smelters, the mint and other activities in Ekaterin- 
burg. 

8 Hcex, 56°59' N, 60=23' E. 

« CxaHOsafl, Stanovaya, 56°52' N, 6i°o' E. 



CHROMATES OF LEAD 383 

but work was discontinued in 1765 because the gold ore pinched out with depth, 
another was being worked in a desultory way by unemployed miners, and a third 
was actively producing in 1770. Two other important mines were the Romanofskoi 
and Khoutschefskoi.^ The first of these was opened in 1762 by 14 shafts, but many 
of these shafts failed to penetrate the overlying gravels and many workings were 
in barren veins. The Klioutschefskoi^ opened a year later : it operated through 
26 shafts with ten sumps and horse-operated pumps. It was a good producer but 
water seepage was a severe problem. Close to Berezov were four more mines, all 
in active production since 1752. These were the Numbers 6, 7, 12 and 24 or Per- 
dounofskoi,^ all near the river, with shafts from 30 to 60 feet deep, but flooding was 
no problem. Approximately 500 miners worked in the district and received from 
three to six kopeks per day depending on need and ability. The gangue was crushed 
and washed in mills near Berezov. 

Pallas did little analytical work on crocoite. He found that it contained 43% 
lead, and yielded a little grain of silver, using crocoite from near Totschilnaia-Gora 
for his tests. 

Crocoite, or plomb rouge, had a bad time of it at the hands of chemists and 
mineralogists for the three decades after its discovery by Lehmann. P. Davila & 
J. Rome de ITsle (1767) described three fine specimens from 'Catherinebourg en 
Siberie' but said that the mineral was lead mineralized with arsenic and sulphur. 
A little later (1772) Rome de ITsle (who called the mineral 'plumbum hexaedrum 
rhombeum fulvum') said that it occurred with quartz, ores of iron and copper, and 
occasionally galena (Lehmann had already noted argentiferous galena as an impurity). 
A. G. Werner (1774) described the crystals as four-sided prisms (as seen in the collec- 
tion of a Dr Schreber), but made no comment on the chemical composition. 

B. G. Sage (1777) found 60 to 72% lead in plomb rouge* and called it an 'acide 
marin' with lead, coloured red by iron.^ R. Kirwan (1784) misquoted Lehmann as 
demonstrating the presence of sulphur, arsenic and 34% lead in plomb rouge 
(Kirwan called it 'red lead spar') - an error that seems incomprehensible. But in 
most of Kirwan's works there is a misprint of 34 for 43% lead* (the correct value is 
given on p. 410 of the 1784 edition), and C. A. Hoffmann (1789, pp. 449, 473) took 
him to task for this error. 

Louis Macquart travelled to Russia by order of the French Government in 1783 
and obtained a considerable quantity of plomb rouge. He was given specimens by 
the Demidoffs and Prince Scherebatoff, and bought other pieces in St Petersburg. 
In 1789 he correctly quoted Lehmann's chemical results and made the helpful 
observation that Lehmann must have considered the mineral to be a 'chaux' (i.e. 
a calx or oxide) of iron and lead (Macquart, 1789). Evidently, to Macquart 'spath 
seleniteux' had no special implication as to radicals in the mineral. Upon his return 

1 These are adjectival forms, from Pomehob, Romanov, and Kjiioh, Klyuch. 

^ Pallas says: 'On m'a assure qu'il existoit, au fond de la mine de Klioutschefskoi, une masse 6norme 
de topaz . . .'. 

' An adjectival form from HepflyHOB, Perdunov. 

* PbCr04 contains 64-11% Pb. 

^ Noted by Monnet (1779) who points out that Siberian plomb rouge differed from flesh-coloured lead 
ores from Poullaouen and Valgouet. 

' Presumably, but not certainly a citation of Pallas' determination. 



384 



THE NATURALLY OCCURRING 




Fig. I. Crocoite, Berezov ; after Haiiy, 1801. 



to France he gave the crystaUine material to Rene Just Haiiy for study. Haiiy 
recognized two habits characterized by elongation in two possible directions, and 
some of his crystal drawings are figured in his Traite (1801). The largest crystals 
were 10-12 lignes^ long and were loosely attached to their quartz gangue. 

Macquart also described the associated species on these specimens. One of these 
was probably vauquehnite (see later). Another was a crystalline mineral that had 
the colour of native sulphur. This was probably cerussite stained with chromates. 
Another yellow mineral, in slender needles, was probably vanadinite or pyromorphite. 
And what Macquart described as 'oxide jaune ou ocre de plomb' (seen on specimen 
No. 24, misprinted 34) was possibly embreyite. 

Assisted by L. N. Vauquelin, Macquart (1789) attempted an analysis of plomb 
rouge and obtained : Pb 36^%, O 37!, Fe 24!, alumina 2 (totalling ioof%) ; the 
excess he attributed to moisture in his precipitates. ^ 

Macquart discussed the use of pulverized plomb rouge as an orange pigment for 
painters, noting that it should be superior to arsenic sulphides, which tended to 
darken in the French climate. E. M. L. Patrin, who visited Berezov in 1786, was 
concerned about the supply of pigment from the mines. The best vein of crocoite 
had pinched down to the width of two pousses^ by this time, and no good material 
had been found for 15 years. As the supply of the mines dwindled, the price of 
specimens soared, and Soret (1818) mentioned that 'D'immenses druses, provenant 
du cabinet de Sitnikoff , ont ete bocardees pour cet usage [as a pigment for ceramics] ; 
plus les cristaux sont nets et transparens, plus ils sont recherches'. 

B. F. J. Hermann (1789) visited Berezov at about the same time as Macquart. 
He placed the time of first mining there at 1744, and milling began in 1752 - a 
date matching that given in Rose's (1837) production tables. Hermann performed 
some chemical tests on plomb rouge and cited Lehmann's analysis of about 50% lead 
plus iron, but said it also contained silver and carbonate. He called the mineral 
'Minera plumbi spathosa', and referred to additional occurrences at Totschilnaja 
Gora (Tochil'naya Gora) and at Poelstaja Prepost near Ui.* 

1 A ligne is 2-12 to 2-26 mm. 

2 i.e. he found 13 grains of lead in 36 grains of sample, hence the peculiar fraction. 

3 A pousse (inch) is 25-40 to 27-07 mm. 

* Poelstaja Prepost was not located; the River Ui (Vh, Ui) is south of Sverdlovsk, and a portion of 
its course is the boundary between the Chelyabinsk Oblast and Kazakhstan. 



CHROMATES OF LEAD 385 

I. von Born (1790) and J. F. Gmelin (1790) were the first to mention crocoite 
localities outside Siberia. Born's locality was Reczbanya^ in Hungary. Gmelin 
grouped all red lead ores together as one species, but doubtless only red lead from 
Berezov was crocoite. T. Bergmann et al. (1792) gave little data in their text. 
They cited a prism angle of 62° (Hauy in Macquart, 1789, had given 60°), and they 
referred only to Macquart's analysis. The mineral was called 'plomb mineralise 
par I'air pur' (i.e. oxygen). 

J. J. Bindheim (1792) in Moscow seriously questioned the older analyses. He 
examined crocoite ('sibirischer rother bleyspat') and determined a specific gravity 
of 5750.2 The first determination had been made by M. Brisson (1787) who 
obtained 6-0269. Bindheim's chemical analysis gave : 'hergestelltes Bley 60%, 
Molybdansaure ii|%, Nickelkalk (mit Inbegriff des geringen Gehalts von Kobold 
und Kupffer . . .) 5|%, Eisenerde 1%, luftleere Kalkerde 6%, Kieselerde 4^%, 
fliichtige Bestandteile 5%, Verlust 6i%'. Bindheim doubted von Born's report of 
crocoite from Retzbanya, and thought it must be a different mineral. 

By now the authors of mineralogical texts were, understandably, confused. How 
could chemists such as Lehmann, Macquart and Bindheim disagree so completely? 
All agreed only upon the fact that the mineral contained lead. Kirwan (1796), 
for example, cited both Bindheim and Macquart and, forced to choose, sided with 
Bindheim. He also reported (p. 214) that 'In France it is said to have been found 
massive, but more generally disseminated or overlaying') ; but no French authors 
have mentioned this. 

The problem was to be resolved by N. L. Vauquelin who made a remarkable 
discovery. Vauquelin had worked as an assistant to Macquart and was not satisfied 
with their analysis. In 1797 he stated that he had come to believe that plomb rouge 
contained neither molybdenum, cobalt, nickel and copper (according to Bindheim) 
nor iron and aluminium as Macquart and he had earlier found. Vauquelin even said 
that he and Macquart had searched in vain for Lehmann's arsenic! This is a 
surprising statement because Lehmann also had sought it in vain and Macquart 
correctly quoted Lehmann as faiUng to find it. 

Vauquelin's experiences with plomb rouge indicated to him that it contained a new 
metal and lead only (and oxygen, of course). The metal present gave a variety of 
colours to its salts so he called it chrome^ following a suggestion by R. J. Haiiy ; 
elsewhere {Crells Chem. Annln, 1798) he credited both Haiiy and A. F. de Fourcroy 
with the suggested name. He also synthesized crocoite by mixing potassium 
chromate (obtained in the course of his analysis) and lead nitrate solutions and his 
analyses of the natural and artificial material are : natural, PbO 63-6%, CrOg 
36-4 (by difference);* synthetic, PbO 65-12%, CrOg 34-88 (by difference). 

His discoveries were widely published, with first notices considerably earlier than 
the dates of 1797 or 1798 given by many writers. The first notice appeared in 1794 

^ Retzbanya, R6zbanya, now Baita, distr. Bihor, Romania, 46°29' N, 22°38' E. 

2 In Kirwan's 1796 edition this is misprinted as 5-50 but was corrected in later editions. 

^ Chromium first appears in D. Reinecke's translation (Crells Chem. Annln, 1: 183 (1798)). 

* This analysis has been mistakenly referred to Thenard by Jameson (1837) and Phillips (1823). In 
the most widely quoted version of Vauquelin's results (/. Mines, Paris, 1797) the analysis for PbO is 
misprinted as 63-96% on p. 760 and 6-86% on p. 744. These misprints have been faithfully copied 
elsewhere, e.g. in Crells Chem. Annln, 1798; Suckow (1804) explains the 6-86% as 'Sauerstofi', giving 
57-10% 'Blei', 36-04% 'Chromsaure'. 



386 THE NATURALLY OCCURRING 

with a note, added in proof, that he had just succeeded in isolating the metal. ^ 
The name chrome appeared in 1796. Vauquelin also observed that only crystal 
fragments or broken specimens were pulverized for pigment : the good pieces, he 
said, adorned mineralogical cabinets throughout the world. 

Vauquelin's discovery was generally accepted by the scientific community, but 
there were a few notes of discord. M. Klaproth (1798) lamented that he had not had 
enough material to name the new metal since his experiments had led him to beheve 
that crocoite contained one ; as a result, some later writers have cited Klaproth as 
co-discoverer (Partington, 1962). More amusing was a blast by Sage (1800) citing 
a fictitious analysis by Vauquelin (neither Thenard^ nor I could find it) given as : 
plomb 36%, acide chromique 37, fer 24, alumine 2. This analysis shows suspicious 
similarities to Macquart's except that 'acide chromique' replaces oxygen. Sage 
then proceeded to present his 'correct' analysis : antimoine 45% (actually 'par 
quintal'), chrome, plomb and alumine ('N'ayant pu separer avec precision le plomb, 
je ne precise que la quantite d'antimoine'). L. S. Thenard (1800) immediately re- 
sponded with a vigorous and amusing defence of Vauquelin. He extended himself 
very far, however, to show that Sage's material was contaminated with gangue,^ 
for he presented an analysis of gangue showing 19% SbgOg. Stibnite does occur 
at Berezov but is rare, and it is almost inconceivable that Sage could find 45% Sb 
and not notice stibnite as the impurity. Thenard then analysed crocoite, using 
Vauquelin's procedure, and found : PbO 64%, CrOg 36. 

VANADIUM MISTAKENLY IDENTIFIED AS CHROMIUM 

In Mexico, A. Del Rio (1804) had a brown lead mineral from Zimapan, which he 
rightly thought contained a new element. He planned to call the element pan- 
chromium, then erythronium,* and his analysis showed 8072% PbO and 14-8% 
erythronium but when he heard of Vauquelin's discovery he thought it might be 
chromium instead.^ He sent some material to Humboldt in Paris but the ship sank, 
and Humboldt's own specimens (brought back by him earlier) found their way to 
H. V. CoUet-Descotils (1804-5) who published an analysis :® 'plomb metalUque 
69%, oxigene presume 5*2%, oxide de fer insoluble dans I'acide nitrique 3-5%, 
acide muriatique sec 1-5%, acide chromique 16%, perte 4-8%'. J. C. Delametherie 
(1806) later said : 'Delrio, savant mineralogiste de Mexico, avoit soup^onne que cette 
mine contenoit un nouveau metal. Sans doute sera le chrome qui I'aura induit en 
erreur.' Del Rio gave up and lost his chance to discover vanadium. His specimens 
found their way to the Museum fur Naturkunde in Berlin, where Humboldt's labels 
were corrected in Rose's handwriting to 'vanadium Bleierz' some 30 years later 
(Weeks, 1935). But some writers continued to cite the original analysis, and hsted 

1 From the description, it was probably one of the chromium carbides. 

2 Thenard : 'Ofi le citoyen Sage a-t-il pu puiser cette analyse si fausse du plomb rouge, qu'il attribue 
si leg^rement au cit. Vauquelin?' 

3 Elsewhere he said that Sage probably confounded muriate of lead with muriate of antimony. 

* See also Humboldt (1804) : 'In dem braunen Blei von Zimapan hat Herr Delrio . . . ein von chromium 
. . . sehr verschiedenes Metall entdeckt, welches er fur neues halt, und . . . Erithronium gennant hat'. 

* Del Rio (1804) : 'pero habiendo visto en Fourcroy que el acido cr6mico da tambien por evaporacion 
sales roxas y amarillas creo que 61 plomo pardo es un cromato de plomo . . . ser' ; see also Del Rio (1822). 

^ Misprinted in part in Eschwege (1820). 



CHROMATES OF LEAD 387 

the mineral as a chromate long after this (Dufrenoy, 1856). Wohler re-examined 
the Zimapan mineral, and recognized that it contained the metal then newly dis- 
covered in Taberg iron by Sefstrom (postscript by P. [Poggendorff] to Sefstrom's 
paper, 1831). In 1833 Rose showed that Berezov 'braunes Bleierz' was identical 
with the Zimapan mineral, which Kobell (1838) later named vanadinite. 



LATER OBSERVATIONS ON CROCOITE 

J. B. Richter (1800) published another early analysis of crocoite. This has 
been virtually forgotten and I have seen it referred to only in Klaproth and Wolff 
(1807). His analysis is : PbO 72-3%, CrOg 27-7. The analysis appears to have 
been carefully done ; chromate was weighed as the green oxide (CrgOj). C. H. 
Pfaff (1816) published an analysis giving : PbO 67-9125%, CrOg 31725 (totalling 
99-6375) and two years later J. J. Berzelius published two analyses : crocoite, PbO 
68-50%, green chrome oxide 24-14, oxygen lost (calc.) 7-56 (totalling loo-oo) ; syn- 
thetic, PbO 68-259% ^^^d CrOg 31-761. The method of his synthesis was that of 
Vauquelin. 

B. F. J. Hermann (1803, 1804) added some interesting notes on the Berezov 
locality as it was in about 1800. He described branching or arborescent gold 
specimens several inches long, but said that they had not been found for some time. 
He also noted that no new localities for chromates had been found recently and that 
in the mines where they did occur pods of galena rimmed with chromates were only 
occasionally encountered. Haiiy also gave some notes of interest in the 1801 edition 
of his Traite. He said that the chromates were worked out about 1760 (undoubtedly 
an error - Patrin's approximate date of 1771 is far more likely) and that some good 
crystals had later been found in isolated pockets together with clay. The veins 
ran north-south, parallel to the banding in the quartz-mica-schist wallrock and 
also carried wulfenite, pyromorphite and anglesite. His crystallographic observa- 
tions then led him to the conclusion that the base of the primitive form of crocoite 
was normal to the prism. In 1809 he said that the base was inclined 'some degrees' 
to the prism, and in 1822 he gave /3 as I03°i6'. In this later work he also told of a 
mine official who sold a specimen for its weight in Russian coinage, an equivalent of 
680 francs. Truly, as he said, 'le plomb rouge se vend tres cher, meme en Siberie'. 

Wiedemann (1801) described a specimen in VilUer's collection in Metz, which 
was i\ Fuss across with crystals 2 to 2\ Zoll long and \ Zoll thick. ^ It was also 
coated in places with 'the usual red, yellow, and green minerals'. What has become 
of this fabulous specimen is not known. 

Vauquelin evidently had a keen eye on the commercial value of synthetic lead 
chromate as a pigment, for he mentioned his hope of finding some more common 
chromium mineral. This was very soon realized by the discovery in 1797 in Var, 
France, of chromite. This was first analysed by F. Tassaert (1797),^ who gave it to 
Vauquelin, who reanalysed it. Later, chromite was found in Siberia and analysed 
by A. Tangier (1811). 

1 A Fuss is about a foot, a Zoll about an inch. 

* Not by Vauquelin, who usually is given the credit, as by A. F. Silvestre (1799), for example. 



388 



THE NATURALLY OCCURRING 



Vauquelin (1809) experimented with the colours of chromates of lead precipitated 
from neutral, acid and alkaline solutions. He noted that alkaline solutions gave the 
reddest precipitates and also observed that an excess of lead oxide in lead chroma te 
gave richer reds. These prophetic observations were soon followed by a paper by 
P. L. Dulong (1812) who boiled a solution of potassium chromate and lead carbonate 
and obtained a rich red precipitate that in nitric acid turned yellow 'en cedant oxyde 
de plomb'. 

J. F. L. Hausmann (1813) called crocoite 'Kallochrom' and gave a very interesting 
account of the Berezov chromates. Most important are his remarks on one species 
that he observed ; '. . . ein anderes Mineral vor [kommt], welches nach meinen 
Versuchen chromsaures Blei zu enthalten scheint und eine genauere chemische 
Untersuchung verdient. Es ist theils dunkel ocherbraun, theils dunkel leberbraun ; 
giebt aber ein zeisiggriines Pulver. Im Bruche eben, einer Seits in das Flachmusch- 
liche, . . . .' This is the first clear description of embreyite. This description was 
read with interest by Ullman (18 14), who described his collection of specimens in 
great detail. Some of these clearly contained not only vauquelinite but phoeni- 
cochroite. 

J. L. De Bournon (1813) disagreed with Haiiy's early crystallographic data for 
crocoite, stating that the primitive form is a prism with angles about 85° and ^ 
about 108°. Probably his crystals were of totally different habit. F. Soret (1818, 
1820) added new forms to the list for crocoite and in 1818 described the primitive 




Fig. 2. Crocoite, Berezov ; after Soret, 18 18. 



form as having ^ I02°5i' and a prism angle of 9i°27' ; in 1820 he gave jS I03°i6' 
and a prism angle of 93°. His specimens were obtained from M. Duval, 'Consul 
general de la Confederation Helvetique, en Russie' and M. Jurine. H. Dauber 
(1859, i860) gave crystallographic data for crocoite that have been widely cited. 



CHROMATES OF LEAD 
S 



389 




Fig. 3. Crocoite, Beresov ; after Kupffer, 1827. 



He measured crystals from Brazil and the Philippines as well as from Berezov. 
Some fine drawings are presented in his i860 paper. 

J. C. L. Zincken {in W. L. Eschwege, 1820) described a new occurrence of crocoite 
in Brazil. He described one specimen of 36 square ZoU with crocoite crystals (of 
'. . . mittlerer Grosse, klein und sehr klein') scattered on sandstone. The crystals 
were partly covered with earthy pyromorphite. The locality given was Conconhas 
do Campo. 

F. Mohs (1824) in his Grundriss der Mineralogie listed crocoite as 'hemiprismatis- 
cher Blei-Baryt'. He cited Pfaff's analysis and gave a specific gravity of 6-004 for 
Siberian material. This value was determined and published later by W. Haidinger 
(1825) and must have been previously communicated to Mohs. In 1827 A. T. 
Kupffer presented new measurements for crocoite, including a prism angle of 
93°44', with one crystal drawing. He had been to the Urals (1829) and discussed the 
geology of the range in some detail. He had also described visits to the Berezov 
gold mines but never mentioned chromates. He did note, however, that the largest 
gold nugget found to date weighed 26 pounds. 

A. Wehrle (1832) reported the occurrence of crocoite ('hemi-prismatisch Bleibaryte') 
at Retzbanya, as von Born had done more than 40 years before ; he was unaware of 
von Bern's paper as well as of the fact that Bindheim had been doubtful of von Bern's 
identification. Despite the confident sound of the title of his paper, Wehrle admitted 
that he did not know whether the Retzbanya mineral was crocoite or vanadinite. 

F. S. Beudant {1832) proposed the name crocoise from the Greek KpoKoeis, 
'jaune aurore' ; F. von Kobell (1838) modified this to Crocoisit, and A. Breithaupt 
(1841) to Krokoit, and which is the name generally in use in Germany. J. D. Dana 
(1868) appears to have been the first to use the form crocoite, now usual in English- 
speaking countries and which he derived from KpoKos, saffron. H. Brooke and 



390 THE NATURALLY OCCURRING 



Fig. 4. Crocoite, Philippines ; after Dauber, i860. 



W. H. Miller (1852) proposed the name lehmannite in honour of J. G. Lehmann, 
but this name has never gained currency. 

C. Baerwald (1882) published the first new analysis of Berezov crocoite in over 60 
years. Determinations of the optical properties were included in the same paper. 
Baerwald used a specimen borrowed from C. F. M. Websky for this work. His 
analysis was : PbO 68-82%, CrOg 31-16, totalling 99-98. 

A. Liversidge (1895) provides the first analysis of Tasmanian crocoite : PbO 
66-86%, CrOg 30-99, FcaOg 1-02, totalling 98-87 ; sp. gr. 5-92. The crocoite dis- 
coveries at Dundas, Tasmania, had just been made and several mines were producing 
the superb specimens that are now to be found in mineralogical cabinets throughout 
the world. These occurrences have been described in a series of publications by W. 
Petterd (1893, 1896, 1901, 1902, 1903, 1910), and the morphology of the Dundas 
crocoites has been described by Palache (1896) and Anderson (1906). In 1931 R. 
Brill pubhshed cell constants for crocoite, a 7-10 kX, b 7-40, c 6-8o, and accepted the 
morphologically determined angle ^ as I02°27'. Later, S. Ghszczynski (1939) 
demonstrated the similarity of monazite and crocoite and gave : a 7-108 kX, b 7-410, 
c 6-771, j3 i03°37-9'. 

Y. Laurent et al. (1967) described an occurrence of crocoite from central France 
near Nontron. A new chemical analysis was given together with morphological 
data. Very fine but small crystals were found here associated with pyromorphite. 
They did not say if the locality could be the same as that mentioned long before by 
Kirwan (1796). 

VAUQUELINITE 

Macquart (1789) described the minerals accompanying crocoite (plomb rouge) ; 
pyromorphite crystals of clearly hexagonal outline up to four lignes long were 
common. Another green mineral (elsewhere described as black or blackish green) 
occurred in small cuneiform crystals. This was unquestionably the first notice of 
vauquelinite, and Macquart believed he was seeing the mineral described earUer 
by Lehmann as a dark mineral - 'ressemblans a une mine de manganese venue 



CHROMATES OF LEAD 391 

d'Orienbourg'. I doubt this identity and believe Macquart alone should be credited 
with the first mention of vauquelinite. Macquart's specimens nos. 26 and 31 
('plomb noir') fit vauquelinite well ; so do nos. 31, 32 and 33 ('plomb vert noiratre 
cuneiforme'). His tests {Essais, p. 357) showed him that the latter contained less 
than half as much lead as plomb rouge, and that it contained iron. 

Berzelius (1818) named this second mineral of lead and chromate vauquelinite.^ 
His analysis was : CuO io-8o%, PbO 60-87, CrOg 28-33. As will be seen later, the 
analysis was faulty, but the mineral is nevertheless a valid species. Mohs (1824) 
later gave a specific gravity of between 6-8 and 7-2 and noted that the mineral also 
occurred in Brazil. F. von Kobell (1838) inadvertently hinted at future problems 
of identity when he described vauquelinite as sometimes occurring in needles or 
spear-shaped crystals. These would certainly be pyromorphite, and the inability 
of some mineralogists to distinguish between these two green minerals was to lead 
to a number of suspect analyses of vauquelinite. To increase the difficulty, these 
two minerals may occur intimately mixed at Berezov, and G. Rose (1839) ^^.s 
satisfied that the CrOg he found in an analysis of pyromorphite (Berezov material) 
was due to contamination. 




Fig. 5. Vauquelinite, Arizona. 

J. John (1845) described a new mineral, 'Chromphosphorkupferbleispath,' a 
pistachio green to olive brown, fine-grained mineral from Berezov, giving an analysis : 
'chromsaures Blei 45%, Bleioxyd 19-0%, Kupferoxyd 11-20%, Phosphorsaure 4-10%, 
Chromsaure mit Spuren Mangans 7-50%, Wasser 1-78%, schwarzbraunes, noch 
naher zu bestimmendes Oxyd [und] weisses, metallisches Oxyd 11-42%' (totalling 
100-00%). As recognized by Dana (1868), it was probably an impure vauqueHnite. 

John had purchased some specimens of Berezov material in Berlin, and his 
description of one of the associated minerals is of even greater interest. He wondered 
if it could be vauquelinite but wrote : 'Ein nelken- und haarbraunes Erz in diinnen 
amorphen Massen ; matt und wachsartig glanzend, undurchsichtig und kaum an 
diinnen Kanten durchscheinend ; von zeisiggriinem Striche'. This was undoubtedly 
impure embreyite (Williams, 1972). 

In 1867 (again in 1869) A. Nordenskiold described as new a mineral from Berezov 
and named it laxmannite. He was well aware of its similarity to Berzelius' vauqueli- 
nite, but maintained that Berzelius had only given an incomplete description of 
pseudomorphs (of what after what he did not say) . He did not believe that vau- 
quelinite was invalid, however, but that it should stand in isomorphous relationship 

1 He was by no means the first to notice it. After Macquart (1789) it is mentioned by Meder (1799), 
Vauquelin (1801), LudlofE (1804), Thompson (cited by Delametherie, 1806), and finally Ullmann (1814) 
who described it well but stopped short of naming it. Ludloff's description is most unconvincing. 



392 THE NATURALLY OCCURRING 

to laxmannite by phosphate-chromate substitution. His two analyses of lax- 
mannite were : PbO 61-26%, 6i-o6 ; CuO 12-43, 10-85 '> FegOg 1-09, 1-28 ; CrOg 
15-26, 16-76 ; P2O5 8-05, 8-57 ; H2O 1-31, 0-90 (totalling 99-40 and 99-42). Nor- 
denskiold gave morphological data^ together with a crystal drawing. The mineral 
was dark olive to pistachio green. 

When H. R. Hermann (1870) noticed this new description he asserted, with 
justification, that Berzelius had probably overlooked the presence of phosphate in 
his precipitate and calculated it all as chromate.^ Hermann recalculated Berzelius' 
analysis in such a way that it became identical to laxmannite, thereby discrediting 
the latter species. He filled the newly created gap with his own new species, 
phosphorchromite. For this he gave a specific gravity of 5-80. The mineral 
occurred on Berezov specimens as nodules with a partly crystalline dense greenish 
black core overgrown with small dark crystals for which no morphological data 
were given. I have seen a number of specimens fitting this description in the 
British Museum (Natural History) collection, e.g. BM 40448. Hermann's analysis 
was : PbO 68-33%, CuO 7-36, FcgOg 2-80, CrOg 10-13, P2O5 9"94, H2O 1-16, total 
99-72. This material is doubtless a mixture of vauquelinite and the massive un- 
identified material recently described with embreyite (Williams, 1972). 

N. I. Koksharov (KoKmapoB, Kokscharow), formerly inspector of mines at Berezov, 
published (between 1853 and 1888) an important series of volumes on the mineralogy 
of Russia. The Berezov chromates are covered exhaustively in volumes 4 (1862), 6 
(1870), 7 (1875) and 8 (1878). Interfacial angles determined by others for crocoite 
and vauquehnite are tabulated along with new measurements by Koksharov. He 
later came to believe that the chromphosphorkupferbleierz (of John) and phosphor- 
chromite (of Hermann) were near vauquehnite although in an earlier volume he 
had reported laxmannite and phosphorchromite with almost eerie detachment, 
totally ignoring Hermann's arguments. A new analysis by Nicolajew was given for 
vauquelinite : PbO 62-70%, CuO 9-58, CrOg 11-95, P3O2 9-23, volatiles 3-00, totalhng 
96-46. A new specific gravity of 6-06 was also reported. 

Koksharov and Des Cloizeaux (1882) gave morphological arguments to show 
that laxmannite was vauquelinite. They also relegated J. John's chromphosphor- 
kupferbleispath and H. R. Hermann's phosphorchromite to synonomy. This view 
has persisted up to the present without being seriously questioned, and the problems 
that began with von Kobell's identification of needles or spear-shaped crystals 
(actually pyromorphite) as vauquelinite seem to be completely smoothed out. 

PHOENICOCHROITE 

J. Badams (1825) credited Dulong (1812) with the first mention^ of another, 
dark red, synthetic lead chromate, and tried to follow Grouvelle's (1821) recipe for 

^ Dana (1951, vol. 2, p. 652), quoting these, says 'Orientation and axes of Nordenskiold'. This is not 
strictly true: Nordenskiold used a setting with a[ioo] as symmetry axis, and his a and b axes have 
been interchanged. 

2 Berzelius precipitated the filtrate from the separation of lead and copper, containing the chromium 
as Cr3+, with ammonia, and ignited and weighed the precipitate, reporting it as Cr^Oj. It would have 
contained most if not all of the P2O5 present. 

^ Actually, the first mention of a distinct dark red lead chromate was by Vauquelin, in 1809; but see 
Lehmann, 1766, under crocoite (p. 381, footnote 4). 



CHROMATES OF LEAD 



393 



its preparation. He managed to get a 'scarlet sub-chromate of lead' by these 
means and analysed the product to assure himself that it contained no potassium. 
His analysis gave : PbO 38-40%, PbCr04 6o-o. P. Grouvelle's method involved 
the warming of lead chromate in a slightly alkaline solution with or without the 
addition of litharge. Grouvelle had not analysed his product but Badams studied 
the process more carefully in hopes of creating a new red pigment. J. Liebig and 
F. Wohler (1831) prepared a basic lead chromate by fusing lead chromate in potas- 
sium nitrate. The product, after gentle washing by decantation, gave a red salt 
assumed to be basic, but no effort was made to identify or analyse it. 




s. 


C 




7 




a 


1 




d 



Fig. 6. Phoenicochroite, Arizona ; after Williams et al., 1970. 



In 1833 H. R. Hermann described a third new lead chromate from Berezov. It 
is barely possible that it had been artificially created by the workers described above. 
Hermann named the mineral melanochroite because, although red, it was notably 
darker than crocoite. He discovered the species on five specimens in a collection 
of 40 pieces of chromate ore from Berezov. His analysis^ gave : PbO 76-69%, 
CrOg by difference. The mineral was of tabular habit with two good cleavages and 
a specific gravity of 5-75. E. F. Glocker (1839) used the name Phonikochroit 
(meaning dark red colour) to replace melanochroite since, strictly speaking, melano- 
chroite implies black. Hermann, of course, used the name in the sense, dark 
coloured. Two years later A. Breithaupt (1841) proposed the name Phonicit (short 
for phonicites plumbosus) but this name was objectionable owing to its similarity 
to phenacite, a beryllium mineral named in 1833. W. Haidinger (1845) used the 
name Phonicit in his Handbuch, and is usually, and erroneously, given credit for 
proposing it. H. Brooke & W. Miller (1852) used phoenicite for phoenicochroite, 
as did A. Kenngott, but this name was soon to die out. Phoeniccohroite has best 
withstood the test of time and is generally accepted today. 

G. Rose (1837) published an important work on Berezov, which was based on his 
experiences while travelling with A. von Humboldt and Moritz von Engelhardt. 
His observations on the Urals in the vicinity of Berezov comprise the first coherent 
report on the geological setting. And he gave the first clear account of some of the 
associated minerals such as aikinite^ (with an analysis by his brother Heinrich), 
tetrahedrite, dolomite, pyrite and crystalline gold. Analyses of gold are presented 
with complete production figures dating back to 1754. His observations on the 

^ Using a method likely to lose some Pb as soluble PbClj, M. H. Hey, pers. comm., 1971. 

^ A specimen of 'aikinite' from Berezov (BM 57624) was analysed in duplicate by M. Duggan (Phelps 
Dodge Corporation) and gave Bi 56-0%, 55-8, Pb 18-7, i8-8, Cu 5-85, 5-74; this corresponds to a formula 
CuPbBijSj, and the material may be lindstromite. 



394 THE NATURALLY OCCURRING 

three lead chromates found there - crocoite, vauquelinite and melanochroite - are 
accurate but add little to the growing list of physical and chemical data being 
amassed by his contemporaries. He did, however, make some useful observations. 
He noted that until H. R. Hermann described melanochroite, it had been confounded 
with crocoite ('rothbleierz'). As we have seen (this paper, p. 381, footnote 4), this 
confusion probably began with Lehmann, thus giving melanochroite an antiquity 
equal to that of crocoite. Another comment, one I have seen nowhere else in the 
old literature, was that melanochroite tended to cleave at right angles to its plane 
of flattening. This is true, and would serve modern workers in its identification. 
Rose did not mention mine no. 7, which had long since been exhausted. He stated 
that most chromates were being found at the Preobraschenski (Preobrazhenski) 
mine, but its production was small in comparison with the older mines. Melano- 
chroite and vauquelinite, as well as crocoite, were found there but were rare : the 
best vauquelinite locaUty was then the Zwetnoi (Tsvetnoi) mine, a locality I have 
seen mentioned by nobody else. 

W. F. Petterd (1895) described phoenicochroite from Tasmania, under the old 
name melanochroite. It occurred as small dark red 'amorphous' masses on gossan, 
found at the Adelaide Proprietary mine. 

A. K. Temple (1956) reported finding phoenicochroite in the Hopeful vein at 
Leadhills, Scotland, and based his identification on the similarity of its X-ray 
powder pattern with that of a specimen of Berezov material labelled as phoenico- 
chroite at the British Museum (Natural History) ; his specimen (one of two) occurred 
as massive red material with cerussite and leadhillite. Contamination with cerussite 
is to be expected in this association, and comparison of the X-ray powder pattern 
with that of pure phoenicochroite confirms that both his specimen and the compari- 
son specimen are impure phoenicochroite, a conclusion that has Dr Temple's agree- 
ment. 

Temple also described a chromian leadhillite with about 0-5% Cr (determined 
spectrographically) . Most interesting, however, was his partial description of a 
possible (and unnamed) new mineral which was a 'chromian lanarkite'. This was 
found at the Hopeful vein also, as small, elongated bright red crystals with cerussite. 
Spectrographic analysis showed 6 to 15% Cr by weight, and complete X-ray powder 
data were given. If his mineral had no more than 7-2% Cr it would be phoenico- 
chroite with no room left for SO4. The X-ray powder data fit phoenicochroite 
nicely (see Appendix) and show no signs of contamination. I am reasonably certain 
that Temple's 'phoenicochroite' was impure phoenicochroite, and his 'new mineral' 
was pure phoenicochroite. 

P. Bariand & P. Herpin (1962) found phoenicochroite at Sebarz Anarak, Iran, 
with fornacite, iranite (see below), dioptase, diaboleite, etc. (see also Bariand, 1963). 
Unfortunately a modern definition of phoenicochroite by Bariand was refused by 
the French Nomenclature Committee on the grounds that his material was not 
adequately tied to type material. This decision was to cause more problems within 
the next decade. 

D. Adib & J. Ottemann (1970) pubhshed a scanty description of a new mineral 
they had found in Iran. This was a red lead chromate to which they assigned the 



CHROMATES OF LEAD 395 

formula PbCr04PbO and named chrominium. Incorrect cell constants were pre- 
sented without supporting powder data, and no consideration was given to other 
lead chromates. 

Shortly afterwards A. Miicke (1970) described another 'new' lead chromate 
(scheibeite) from Sierra Gorda, Chile. An analysis of sjmthetic material was given, 
after showing by comparison of X-ray powder diffraction data that this product 
was identical to the new mineral. X-ray unit cell data were also presented and 
compared with Bariand and Herpin's and Adib and Ottemann's results. Despite 
the obvious similarities, Miicke put his faith in the analysis (which gave Pb8(Cr04)305) 
and proceeded with the description of what he thought was a new mineral. 

In 1970, I published, with J. McLean and J. W. Anthony, a redefinition of phoeni- 
cochroite. This material had been found in Arizona with other chromates, perhaps 
at the locality B. Silliman, Jr, meant in 1881 (see p. 399). Our data were essentially 
in agreement with those in Bariand's unpublished manuscript, and we had no reason 
to believe that it was not identical to Hermann's phoenicochroite. No specimens 
from Berezov had been found, nor have they since, that failed to match the meagre 
description by H. R. Hermann, nor has more than one species of dark red colour 
been observed in Berezov material. Like Bariand, we saw no reason to question 
the identity of Berezov phoenicochroite. Later in the same year, J. Zemann 
(1970) obtained Miicke's X-ray powder photographs and specimens of Adib and 
Ottemann's chrominium. He took his own photographs and found that they 
matched not only each other but our data for phoenicochroite as well. A recent 
vote by the New Minerals Commission of the International Mineralogical Association 
on this matter has settled the question, reaffirming phoenicochroite as the accept- 
able name for this species. 

SYNTHESES-REAL OR SUPPOSED-OF PHOENICOCHROITE AND OF OTHER 

BASIC LEAD CHROMATES 

Many authors besides Grouvelle (1821), Badams (1825) and Liebig & Wohler 
(1833) have described the preparation of red, basic lead chromates but in most 
cases there is no evidence that the product was homogeneous and in many, no 
chemical analysis. 

N. C. Manross (1852) obtained ruby-red crystals 'viel zu dunkel fur neutrales 
chromsaures Blei', which he thought were phoenicochroite, by fusion of lead chloride 
and potassium chromate. He gave a specific gravity of 6-ii8 for his product but 
no analysis was offered. However, he observed crystals of (pseudo)'^ hexagonal 
habit with a prism angle of ii9°54'. A. Drevermann (1853, 1854) claimed to have 
synthesized phoenicochroite and crocoite by diffusion in water between vessels 
containing solutions of potassium chromate and lead nitrate. No evidence was 
offered. Phoenicochroite was supposed to have formed as small, dark red rhombic 
tablets, crocoite as needles three to four millimetres long. A. Becquerel (1866) 
claimed that he grew phoenicochroite and crocoite using slightly different electrolytic 
methods. Only the colour of the products was cited as evidence. S. Meunier 
(1878) reported a simple procedure for producing phoenicochroite. He had used 

* i.e. he said they were hexagonal but this is contradicted by the prism angle he cited. 



396 THE NATURALLY OCCURRING 

this method successfully to produce brochantite and A. Des Cloizeaux suggested 
that he apply it to produce lead chromates. Fresh galena was put into a solution 
'plus ou moins etendue' of potassium dichromate. After six months the galena 
was covered with a mixture of yellow, green and red compounds and the red (in- 
soluble in water) was shown by physical properties to be phoenicochroite.^ L. 
Bourgeois (1887) described a method for synthesizing crocoite and presented an 
analysis of the product. He also noted that the red rectangular tablets produced 
by Liebig and Wohler could well be melanochroite and, moreover, isomorphous 
with lanarkite. Recent work has confirmed this guess regarding the isomorphism 
of lanarkite and phoenicochroite. 

M. Lachaud & C. Lepierre (1890, 1891) dissolved lead chromate in hot 2N KOH 
solution and obtained yellow-orange prismatic crystals which gave, upon analysis : 
PbO 82-01%, 81-85 ; CrOg 17-95, 18-02, totalling 99-90, 99-87. They also obtained 
a product of rich red colour by fusing lead chromate with salt and obtained two 
analyses : PbO 77-20%, 77-25 ; CrOg 22-55, 22-90, totalling 99-75 and 100-15. 
This product was stated to be orthorhombic with a specific gravity of 5-81, and 
was regarded as synthetic melanochroite. Another fusion product was analysed 
and gave a composition near Pb4Cr50ig. Shortly after, C. Ludeking (1892) claimed 
that he synthesized crocoite and phoenicochroite by permitting a solution of PbCrO^ 
in concentrated KOH to evaporate slowly in air for several months. His analyses 
are : 'crocoite', PbO 63-9%, CrOg 35-2, 99-1 total, and 'phoenicochroite' PbO 71-2%, 
CrOg 25-9, total 97-1. An excess of KOH was said to favour the formation of 
phoenicochroite ; an excess of PbCr04, ciocoite.^ 

M. Groger (1919) prepared a clear red basic lead chromate using the fusion 
methods employed by Liebig and Wohler. Analysis of the product gave : PbO 
8i-o8%, CrOg 18-85 ^Jid CrOg 19-06, 19-00, 19-00, the chromate being determined 
iodometrically. His main concern was proving the efficacy of the iodometric 
method ; his product has been assumed to be phoenicochroite. J. F. G. Hicks 
(1921) prepared a number of basic lead chromates by fusion of PbO and either 
sodium or potassium chromate in a flux of KNOg or NaNOg. He claimed that the 
following salts were obtained : PbO : PbCr04 = 1:2, 1:1, 2:1 and 3 : i. Analyses 
were made of fine-grained reaction products. A widely quoted paper by F. Jaeger 
& H. Germs (1921) dealt with the system PbO-PbCr04 up to 900 °C. They found : 
PbO : PbCr04 = 4:1, 5:2, 1:1 and crocoite. They failed to find salts with ratios 
of 2 : I or I : 2, and expressed doubt about the existence of the 5 : 2 salt (presumed 
to be phoenicochroite). R. Weinland & F. Paul (1923) claimed that they grew 
fire-red crystals from solution which yielded, upon analysis, Pb 75-76%, Cr04 
20-86. They also grew, from perchloric acid solutions, a compound said to be 
Pb0.2PbCr04 analysing 70-97% Pb. 

H. Wagner et al. (1932) also discussed the basic lead chromates and gave X-ray 
data for some of their artificial products. They reported a tetragonal chromate 
but are vague about its composition ; it could be (they said) PbCrO4.PbO.MH2O 

^ My own attempts with a variety of solutions 'plus ou moins etendue' have invariably failed to pro- 
duce phoenicochroite. 

2 I have tried this method with a considerable range of solution compositions. Bright red crystals 
could be obtained but were invariably litharge. 



CHROMATES OF LEAD 397 

mixed more or less with Pb2Cr04(OH)2. H. Wagner & H. Schirmer (1935) corrected 
Wagner's earlier statements about the vaguely defined compound of Pb, Cr04 
and more or less OH and HgO. This could now be shown to be PbgCrOg, which 
appeared tetragonal under the microscope, and gave an X-ray powder pattern 
compatible with a tetragonal cell having a 5-95, c 6-71 A. 

L. Cloutier (1933) reviewed the conflicting reports on the basic lead chromates 
and investigated the aqueous sj^stem Pb(N03)2/K2Cr04/KOH. He analysed 
solution compositions after precipitation and concluded that he could only obtain 
PbO.PbCr04 and 2PbO.PbCr04. He was sceptical of other salts reported by 
Hicks and by Jaeger & Germs. 

FORNACITE 

A new chromate mineral was described by A. Lacroix in 1915. It occurred as 
small crystals in a 'magnificent' geode of dioptase from Djoue, French Equatorial 
Africa (now part of Zaire). No analyses were given but qualitative tests showed 
that it was an arsenate-chromate of lead and copper. He considered its possible 
identity with vauquelinite but said the new mineral differed because it carried 
hydroxide as well as oxide radicals, i.e. it was a basic salt. The colour was given as 
olive green ('like Cornish olivenite') with a yellow streak. The name given was 
'furnacite' but this was soon corrected to fornacite (from fornax, in honour of L. 
Fourneau ; Lacroix, 1916). 

An analysis of fornacite, however, had to wait for C. Guillemin & J. Prouvost 
(1951), who showed that it is the arsenic analogue of vauquelinite. They also gave 
two new analyses of Berezov vauquelinite for comparison, though one of their speci- 
mens had the locality given simply as Ekaterinburg. X-ray powder data, new 
specific gravity determinations, optics and spectrographic analyses were also 
included. They proposed to call such minerals containing more than 7% by weight 
AS2O5 fornacite, others vauquelinite (the 50 mols% division would be at 7-62% 
AS2O5). 

P. Bariand & P. Herpin (1962) examined fornacite from a new locality (Sebarz, 
Iran) and provided a new analysis and an indexed X-ray powder pattern. They 
concluded that it is a valid and distinct species. 

EMBREYITE 

F. Pisani (1880) published another new mineral description based on Berezov 
material. This was referred to as chromo-phosphate of lead and copper and was 
not given a name. His description deserves more careful attention than it has 
received. He wrote that it was botryoidal, red-orange with a yellow streak, and 
had a drusy crystalline surface. To these few tantalizing comments only a chemical 
analysis was added : PbO 70-60%, CuO 4-57, CrOg 15-80, PgOg 9-78. 

In 1968 I found orange to yellow-brown crystalhne material on Berezov specimens 
in the collections of the Ecole des Mines, Paris and on British Museum (Natural 
History) specimen BM 94718 that matched data obtained on a specimen belonging 
to Mr John B. Jago of San Francisco that I had seen in 1963. With this supply of 



398 THE NATURALLY OCCURRING 

better material I undertook the description of a new species, to be named embreyite 
(Williams, 1972). It is a chromate-phosphate of lead and copper very similar to 
and probably identical with that described, incompletely, by Pisani (1880), and was 
possibly first noted by Macquart (1789). Further specimens of this mineral were 
subsequently found at the British Museum (Natural History) in 1971. 

On some of these specimens (BM 94718 and 39319) there is also massive oily green 
to brown material which shows, spectrographically, Pb, Cu, Cr and P. X-ray powder 
patterns of this material are rich in lines and suggest that it is a mixture. However, 
the strong lines in these patterns (several have been taken) do not match any of the 
other lead chromates. A description will have to await the availability of better 
material. 



IRANITE AND HEMIHEDRITE 

P. Bariand (1963) found a number of chromates at Sebarz, Anarak, Iran, and 
together with P. Herpin described a new mineral, iranite, from this locality (Bariand 
& Herpin, 1963) . After microprobe analysis for Pb and Cr, and proof of the presence 
of water by the Penfield method, they assigned the formula PbCr04.H20. The 
water had been determined by difference. The mineral was described as orange, 
occurring as small, measurable triclinic crystals associated with a variety of lead, 
copper and zinc minerals. 

Hemihedrite was described by S. A. Williams & J. W. Anthony (1970) as a new 
triclinic lead zinc chromate from the Florence Lead Silver mine in Arizona. Its 
composition appeared to be unUke that of iranite, and its powder pattern lacked 
many of the lines given by Bariand & Herpin for iranite. Recent work has shown, 
however, that the formula of iranite was incorrectly given, and that numerous 
misprints appeared in the intensities presented in the powder pattern (Bariand, 
pers. comm., 1973). New partial analyses have shown the following : Sebarz, 
type iranite 4-59% CuO, 0-20 ZnO ; Seh-Changi, Iran, iranite 2-29% CuO, 0-43 
ZnO ; Potter-Cramer, Arizona, hemihedrite 0-04% CuO, 2-49 ZnO ; Boulder City, 
Nevada, hemihedrite 0-58% CuO, 1-30 ZnO. Although further work needs doing, 
it is possible that a series from iranite (Cu end member) to hemihedrite (Zn end 
member) may be the solution to the problem. Work done to date shows that both 
species are valid and closely related. 

A recent paper by Adib et al. (1972) tends to confirm this ; an X-ray study of 
topotype material shows that their 'khuniite' is iranite. The role played by fluorine 
and hydroxyl in these minerals is still uncertain, but I beUeve the problems can be 
solved without the introduction of an abundance of mineral names. 



SANTANAITE 

The most recently described lead chromate santanaite (Miicke, 1972), occurs 
sparingly at the Santa Ana mine in Chile. As described, this mineral appears to be 
totally unlike any previously known lead chromate. A formula Pbi^CrOie has been 



CHROMATES OF LEAD 
C 



399 




Fig. 7. Hemihedrite, Arizona ; after Williams and Anthony, 1970. 

assigned, but the oxygen was determined by difference with a probable error of 
± 2%, so that the composition could lie anywhere in the range Pb^iCrOigto PbiiCrOig. 



SOME DOUBTFUL SPECIES 

Jossaite. Breithaupt (1858) described another species from Berezov. No chemical 
analysis was given but chemical tests by Plattner, cited in his paper, indicated that 
it was a chromate of lead and zinc and, possibly, cadmium. The specific gravity 
was 5*2 but Breithaupt was clearly not confident of this value. A prism angle of 
110° to 118° was also given. The colour was orange. Breithaupt had kept the 
material for six years hoping to get more for a complete description and then, 
giving up, published this short note. Jossaite has never had much success as a 
mineral. Only B. Silliman, Jr (1881) has reported it from elsewhere, namely on a 
suite of specimens sent to him from a locality 20 miles north-east of Vulture P.O. 
in Arizona. A number of collectors, notably the late Ed McDole (deceased, 1970), 
have searched for this locality in vain. Recently I found a fine suite of chromates 
the same distance from Vulture P.O. but in exactly the opposite direction. Among 
these was a chromate of lead and zinc, but it does not fit Breithaupt's scanty descrip- 
tion. Furthermore, I have examined a specimen of 'jossaite' from the U.S. National 
Museum (R 6032) and shown it to be crocoite ; it fitted Breithaupt's description 
rather well.^ Jossaite remains a mystery and is probably a myth. 

A. Arzruni (1885), in an important contribution to the geology of the Berezov 
area, lists the minerals found in the district :^ anglesite, azurite, beudantite, bind- 
heimite, bismutite, bismuth ochre, calcite, caledonite, cerussite, chalcedony, chalco- 
pyrite, chlorite, chromite, chrome ochre, chrysocolla, covelline, crocoite, dolomite, 
fuchsite, galena, garnet, goethite, gold, hematite, hydrohematite (= turgite), 
jarosite, jossaite, laxmannite, leadhillite, limonite, linarite, magnetite, malachite, 

1 One might wonder if the mineral could be hemihedrite. I have seen none on Berezov specimens nor, 
for that matter, have I seen any zinc minerals. The only zinc mineral reported by Arzruni (1885) is 
Jossaite (!) of which he asks '. . . ist der Zinkgehalt unzweifelhaft?' 

^ Most authors agree that the Berezov district lies within a rectangle seven versts east-west by eight 
versts north-south with Berezov at centre of the lower edge. 



400 THE NATURALLY OCCURRING 

melanochroite, muscovite, orthoclase, patrinite, plagioclase, pyrite, pyromorphite, 
pyrophyllite, quartz, rutile, scorodite, sulphur, talc, tennantite, tetrahedrite, tor- 
bernite, tourmaline, tremolite, vanadinite, vauquelinite, wad, wulfenite, xantho- 
siderite and zircon. 

Arzruni gave the Preobrazenskij mine as the locality for jossaite but how he knew 
I have been unable to determine. In addition to this list, Arzruni gave abbreviated 
mineral lists for crocoite localities outside the Berezov district. At Bertjowaja 
Gora it occurred with cerussite, galena, malachite, pyromorphite, pyrite and quartz, 
and at Tochil'naya Gora with pyrite, quartz and tourmaline containing, in one 
instance, i-i66% CrgOg. This analysis is not his but that of H. R. Hermann. 

Eosite. A. Schrauf (1871) described a new mineral from Leadhills in Scotland as 
eosite. His morphological data are exhaustively complete, and the crystals are 
clearly close to wulfenite, both in angles and habit. The chemical results are very 
fragmentary, however. He did only qualitative work, indicating that it was a 
vanadian wulfenite, and apparently did not look for chromium. Since we now know 
that a variety of chromates occur at Leadhills, it is possible that eosite contained 
chromate. I have not been able to find a specimen of the original eosite, however. 
A sample so labelled at the British Museum (Natural History) was stored among the 
doubtful species, but proved to be beautifully crystallized phoenicochroite showing 
several new forms and 'butterfly' twinning on {201}. 

'4Pb0.3Cr03'. W. E. Dawson (1886) sent a small sample to the British Museum 
(Natural History) from the Transvaal with an analysis showing PbO 7476%, 
CrOg 25-24, and his letter to the Mineralogical Society was published in the Mineral- 
ogical Magazine. Correspondence files at the British Museum (Natural History) 
indicate that L. J. Spencer and G. T. Prior had quickly shown that the specimen 
(BM 62927) was merely red vanadinite ; this was verified recently on the same 
material by C. J. Elliot by infra-red spectroscopy. Dawson's anatysis, unfortunately, 
has been taken seriously by later workers. There is now no reason to believe the 
analysis, and the 'new chromate from the Transvaal' should be eliminated from 
further consideration. 

Beresovite was described by Ya. Samoilov (CaMOHJioB, ^,; Samoilow, J.) (1897). 
The type locality was Berezov but the material providing the new species came from 
a collection at the University of Moscow. Samoilov gave a fairly clear description 
of this mineral. It occurred in lamellar masses or intergrown crystals, which could 
not be measured but showed good cleavage. The specific gravity (6-69) was deter- 
mined on 2-2 grams with a pycnometer. Associated species were cerussite, galena, 
and crocoite, which may replace it. Three partial analyses were given : 0-6972 g 
gave PbO 79-36%, CrOg 17-93 ; 0-6368 g gave PbO 79-24, CrOg 17-93 ; and 0-6387 g 
gave CO2 2-46. The mineral was said to be pleochroic, red to red-yellow when lying 
on its cleavage, and in this position it showed no trace of an interference figure. 

G. Bischof (1866) called attention to the fact that phoenicochroite may alter to 
crocoite, and his paper shows the first real interest in the paragenesis of the Russian 
chromates. He believed that vauquelinite obtained its copper from malachite and 
linarite, which are earlier-formed species on some specimens. Bischof examined 
specimens from Berezov and Tochil'naya Gora but gave still another locality for 



CHROMATES OF LEAD 401 

chromates : Bertewaja Gora, near Nischne-Tagilsk (Hhmchhh TarHji, Nizhnii-Tagil, 
57°54' N, 58°57' E). Further data on paragenesis were given by Cornu (1909). 

Recent work, especially by R. J. Davis (unpublished), has called attention again 
to the tendency of phoenicochroite to alter to a mixture of crocoite and cerussite. 
Since in other respects Samoilov's description fits phoenicochroite well, it appears 
probable that beresovite is partially altered phoenicochroite. 

Petterd also claimed (1902, 1903) that he had found beresovite, but he gave only 
a visual impression of the material. It was found at the Magnet mine as 'charac- 
teristic crystals', yellow to orange to crimson, implanted on a soft matrix. 

Bellite. Petterd (1910) described a new mineral which he named bellite. It 
occurred at the Magnet Silver and Magnet mines, Tasmania, as delicate red or 
crimson tufts. Crystals were needles of hexagonal outline associated with chromian 
cerussite, crocoite and mimetite. The mimetite might be chromiferous, he said. 
The specific gravity was 5-5 and an analysis by J. D. Millen in London gave : PbO 
6i-68o%, CrOg 22-611, V2O5 o-io6, P2O5 0-045, AsgOg (sic) 6-548, AI2O3 0-012, CI 
0-516, SO3 0-054, Ag tr., SiOg 7-587 totalling 99-159. This mineral was reinvestigated 
by Strunz (1958). The original description had been scanty and L. J. Spencer 
(1907) had said it was probably a mixture of mimetite, quartz and crocoite on the 
basis of the analysis. Strunz's X-ray work showed a strong similarity of the powder 
patterns of bellite (a 10-13, ^ 7'39 •^) ^.nd mimetite. Strunz considered the SiO^ 
in the analysis to be essential ; he wrote a formula, based on those of the lead apa- 
tites, essentially reinstating the species. Shortly afterwards W. Johnson (i960) 
succeeded in preparing a chromium analogue of hydroxyapatite, containing Cr^+ 
and Cr^+, and no phosphate. 

A recent (Tasm. Dept. Mines, 1970) partial analysis of presumed type material 
showed : PbO 70-0%, CrgOg 2-9, ^ AsgOg 14-5, CI 2-5. The authors conclude that 
bellite is mimetite mixed, in their analysis, with crocoite in the approximate ratio 
of 10 : I, thereby invalidating the species. 



A SUMMARY OF THE VALID AND DOUBTFUL SPECIES 

Of the minerals that have been discussed crocoite (PbCrOJ is truly the head of the 
family. It was the first found, is the most common and has suffered the least 
abuse at the hands of mineralogists during the past two and a half centuries. Its 
status or validity has never been questioned and it is now well described. Only its 
nomenclature has been confusing, and crocoite only gradually emerged as the accepted 
name after its first use by Breithaupt in 1841. 

Phoenicochroite (PbgCrOg) was noted as early, and its history is about as long as 
that of crocoite, but its description had to wait until 1833. It has suffered some name 
changes and was largely ignored except by chemists who continually reported its 
synthesis. The original analysis was faulty, and this has led to considerable con- 
fusion and some wishful thinking. Nobody has satisfactorily demonstrated that he 
can produce a red chromate matching H. R. Hermann's formula (2PbCr04.PbO), 

1 The value 2-9% Cr^Oj is compared with Petterd's (1910) value of 22-611% for CrOj, given here as 
22-61% CrjOj. 



402 THE NATURALLY OCCURRING 

but over the years artificial preparations with compositions near PbgCrOg have 
been obtained, and, as has been recently shown, this is the composition of phoeni- 
cochroite. Phoenicochroite alters readily to a mixture of crocoite and cerussite, 
and it was almost certainly such a mixture that Samoilov analysed and named 
beresovite. The recently described scheibeite and chrominium (p. 394-5) have the same 
unit cell constants and other properties as phoenicochroite and are clearly identical 
with it. 

Vauquelinite {Pb2CuCr04P040H) is the third lead chromate mineral to be recog- 
nized - it was described clearly by Macquart in 1789 but was not named for another 
29 years. The original analysis was probably faulty, as Hermann (1870) maintained, 
but this has not cast any doubt on the validity of the species as was the case with 
phoenicochroite. But vauquelinite has undoubtedly been confounded not only with 
pyromorphite, but with embreyite and the intimate mixture of two or more other 
species that I have found. Scrutiny of analyses made by later workers strongly 
suggests that they have analysed mixtures. Further work, particularly analyses 
of pure Berezov material, is desirable. 

Fornacite (Pb2(Cu,Fe)Cr04(P,As)040H) is probably isomorphous with vauquelinite 
according to the structural studies of Fanfani and his colleagues, but despite the 
dubious material that has been anatysed in the past, there may well be a threefold 
series between the chromate, phosphate and arsenates of lead and copper. Analyses 
done to date, if believed, suggest considerable substitution of CrOg for P2O5, and of 
CrOg for AsgOg and vice versa. Should further work support these views, lax- 
mannite might well be reinstated for the phosphate end member. 

Iranite and hemihedrite are remarkably similar, and at one time I thought they 
were identical. Recent electron probe analyses on Bariand's type specimen and his 
second occurrence material (also in Iran) have both shown less than 0-05% Zn, 
whereas hemihedrite has considerably more and contains no Cu. Since the unit 
cells of the two minerals can be transformed to near identity, and all other properties 
are very similar, it seems probable that there is a series, partial or complete, between 
the two species with Zn and Cu replacing one another. 

Embreyite, Pb5(Cr04)2(P04)2.H20, stands alone - it is unlike any other chromate 
mineral -but Pisani's analysis should probably be placed here (see p. 397). This 
anatysis has previously been included with the vauquelinites, from which it differs 
mainly in having more lead and less copper. The other massive phases, known at 
present only by their powder patterns, are probably inextricably mixed in the 
chemical analyses of some of the Russian vauquelinites. More work needs to be 
done. 

Santanaite is clearly a valid species, though its formula remains uncertain. 

Eosite remains a mystery. Artificial tetragonal lead chromates have been described, 
but whether they are completely isomorphous with the lead molybdates is doubtful. 
It is not even certain yet whether or not eosite should be classed as a molybdate- 
vanadate or a molybdate-chromate. More work needs to be done, and Schrauf's 
original material, if it could be found, would be essential for this. 

Bellite may eventually stand as a valid species even if the original analysis was 
carried out on a mixture. Chromate can enter into mimetites or similar structures, 



CHROMATES OF LEAD 403 

and a chromate analogue of apatite has been artificially prepared. There is an 
abundance of such minerals at Leadhills and in the Arizona (Wickenburg) locality, 
and some of these Arizona mimetites are highly chromatian. Analysis of a specimen 
from Wanlockhead (Vernon, 1827) showed only i-20% PbCr04, however ; and 
Temple (1956) found less than 1% Cr in a Leadhills specimen (pers. comm., 1964). 
Discrediting the Tasmanian material need not affect the potential validity of the 
mineral. 

Jossaite is difficult to discredit since there are no authentic specimens, to my 
knowledge, extant. A specimen from the United States National Museum (catalog 
R6032) did not have good credentials, but it is highly suggestive that the crystals 
on this piece fit Breithaupt's description well - and are crocoite. I have seen no 
sign of the lead zinc chromate hemihedrite in the Berezov material, and in fact have 
not yet seen any zinc mineral from that locality : so jossaite must remain highly 
doubtful. One must wonder, however, about the positive zinc test jossaite gave 
Plattner ; also bothersome is the fact that Breithaupt considered jossaite younger 
than vauquelinite. On Berezov specimens it is usually obvious that crocoite is 
older. 

SUMMARIZED DATA FOR THE SEVERAL SPECIES 

Crocoite, PbCr04 ; monoclinic, 2/m 

Some other names are : minera plumbi specie crystalUne rubra (Lehmann, 
1766, 1767) ; plomb rouge (Davila & de ITsle, 1767 ; also Sage, 1769) ; mine de 
plomb rouge (Pallas, 1770) ; plumbum hexaedrum rhombeum fulvum (de ITsle, 
1772) ; roth bleyerz (Werner, 1774) ; minera plumbi rubra (VVallerius, 1778) ; red 
lead spar (Kirwan, 1784) ; oxide de plomb combine avec oxide de fer (Born, 1790) ; 
plomb mineralise par Fair pur (Bergmann et al., 1792) ; plomb chromate (Haiiy, 
1801) ; Kallochrom (Hausmann, 1813) ; chromate of lead (Phillips, 1823) ; hemi- 
prismatischer Blei-baryt (Mohs, 1824) ; chromsaiires Blei (von Leonard, 1826) ; 
crocoise (Beudant, 1832) ; Chromspath (Breithaupt, 1832) ; Crocoisite (von Kobell, 
1838) ; Krokoit (Breithaupt, 1841) ; lehmannite (Brooke & Miller, 1852) ; beresofite 
(Shepard, 1852). 

Physical properties : Crocoite is bright to dull orange to orange-red with an orange 
streak. Typical Berezov specimens gave colour matches (Royal Horticultral 
Society) such as 34C (grenadine red), 44B and 32 A (Indian orange). A typical 
Dundas specimen was 41B (vermilion). The streak is 23 A (cadmium orange) to 
24A (tangerine orange). 

Specific gravities ranging from 5-75 to 6-29 have been reported ■} the more 
reliable data range from 5-99 to 6-12 (calc. for PbCrO^ with Pistorius & Pistorius 
cell dimensions, 6-ii). H. 2\ to 3. 

Crocoite is slightly pleochroic in shades of orange ; a 2-29, j8 2-36, y 2-66 all 
±0-02, 2Vy 57°, all for Li (Larsen, 1921) ; 2Vy 54°3' for Na, /3 || [010], y. [001] 
5°3o' in the obtuse angle ^ (Des Cloizeaux, 1882). 

1 60269, Brisson, 1787; 5-75, Bindheim, 1792; 6-004, Haidinger, 1825; 6-004, Breithaupt, 1841; 
6-118, Manross, 1852; 5-965, Schroder, 1874; 6-29, Bourgeois, 1887; 5-92, Liversidge, 1895; 7-123, 
Schulten, 1904; 6-o6, Quareni & Pieri, 1964; 6-12, Laurent et al., 1967. 



404 



THE NATURALLY OCCURRING 



X-ray data : The space-group is P2jn (Quareni & Fieri, 1964) ; Z = 4. Cell 
dimensions have been determined by several authors (Gossner & Mussgnug inter- 
changed the a and c axes) : 



Gossner & Mussgnug, 1930* 
Brill, 1 93 1* 
Gliszczynski, 1939* 
Pistorius & Pistorius, 1962! 
Williams, on B.M. 40448 

* Cell dimensions converted from kX. 
t a, 6 +0-006; c +0-004. 



a 


b 


c 


7-17 A 


7-49 


6-83 


7-II 


7-40 


6-81 


7-122 


7-425 


6-785 


7-122 


7-425 


6-785 


7-120 


7-421 


6-8oo 



I02°27'\ 

n.d. J 



Locality 
Not stated 



io3°38' Berezov 
io2°27' Berezov 
io2°2o' Berezov 



The strongest X-ray powder diffractions reported are 



hkl 
on 
iiT 
200 

102, 120 
210 
012 

103, 131, 221 
132, 322 

^ 'Jossaite'. 



Pistorius & 


Williams 




Williams 




Williams 


Pistorius, 


1962 


BM 40448 




USNM R6032 


Wickenburg 


Synthetic 


Berezov 




Berezov 1 






d 


/ 


d 


/ 


d 


/ 


d I 


4-951 A 


18 


4-950 A 


3 


4-935 A 


3 


4-939 A 5 


4-378 


27 


4-374 


5 


4-372 


4 


4-370 6 


3-476 


85 


3-475 


8 


3-479 


9 


3-477 10 


3-276 


100 


3-277 


10 


3-273 


10 


3-274 10 


3-148 


18 


3-150 


I 


3-149 


2 


3-150 2 


3-027 


30 


3-030 


6 


3-017 


8 


3-018 9 


2-253 


19 


2-254 


5 


2-250 


4 


2-250 6 


1-846 


21 


1-846 


3 


1-848 


4 


1-848 6 



Chemistry : In the following table of analyses, the original data have been re- 
calculated using modern atomic weights wherever the author has described his 
methods in sufficient detail. In several cases computational errors in the original 
have been found. 



PbO 
Cr03 


I 
53-9% 


234 
46.3 65 to 77 64.6 


5 
38-9 


6 
60-8 

[39-2]* 


7 
65-0 
24-9 


8 
62-2 

[37-8]* 


PbO 


9 

-1- 


10 II 

67-91 68-50 


12 

68-82 


13 

66-86 


14 
68-35 


15 
69-06 


Cr03 


+ 


31-725 31-76 


31-16 


30-99 


30-35 


30-94 


*By 


difference. 













1. Lehmann, 1769 

2. Pallas, 1773 ; also Ag present 

3. Sage, 1777 ; also Fe and CI present 

4. Bindheim, 1792 ; also FejOg 1%, M0O3 
11-7, SiOj 4-5, NiO 5-7, CaO 6, volatiles 
5, Ag trace. 



5- 
6. 

7- 



rO/ 



Macquart, 1789 ; also AI2O3 5-1' 

Vauquelin, 1797 

Richter, 1800 ; also impurities 10-1% 



8. Thenard, 1800 

9. Sage, 1800 ; Sb 45%, AI2O3 present 

10. Pfaff, 1816 

11. Berzelius, 1818 

12. Baerwald, 1882 

13. Liversidge, 1895 

14. Laurent, 1967 ; also SiOj 1-10% 

15. Theory for PbCr04 



\ 



CHROMATES OF LEAD 



405 



Paragenesis : Crocoite has a fairly broad range of stability in the paragenesis 
of chromates. It may form very early but is later than anglesite and phoenicochroite. 
At Berezov it is often earlier than cerussite, and has formed at the expense of 
phoenicochroite or by replacement of anglesite. This is particularly true of those 
partially oxidized specimens with remnants of fresh galena. With continuing 
oxidation crocoite may form along with cerussite, and in such cases it may be 
deposited on fracture surfaces some distance from the 'parent' galena. If copper or 
zinc is present crocoite is eventually replaced by iranite, hemihedrite or vauquelinite. 



Phoenicochroite, PbgCrOg ; monoclinic, zjni 

The nomenclature of phoenicochroite was : Melanochroit (Hermann, 1833) ; 
Phonikochroit (Glocker, 1839) ; Phonicites (Breithaupt, 1841) ; Phonicit (Haidinger, 
1845) ; phoenicochroite (Nicol, 1849) ; phcenicite (Brooke & Miller, 1852) ; Phonizit 
(Breithaupt, 1852) ; heresowite (Samoilow, 1899) ; scheibeite (Mucke, 1970) ; chro- 
minium (Adib & Ottemann, 1970). It was probably the mineral 'the colour of 
Japanese cinnabar' noted by Lehmann (1766). 

Physical properties : Phoenicochroite is rich cochineal red with an orange or 
yellow-orange streak. H. 2\. Specific gravity 7-01 (calc. for PbgCrOg, 7-07). 
Crystals tend to be tabular prisms and exhibit a very smooth cleavage on (201). 
The refractive indices are : for Li, a 2-34, ^ 2-38, y 2-65 (Larsen, 1921) ; for Na, 
a 2-38, j8 2-44, y 2-65, with 2Vy 58°, a |] [oio], j8 I [ooi] 2° in the obtuse angle ^ 
(Williams, 1970). 

X-ray data : The space-group is Czjm ; Z = 4 ; the following cell dimensions 
have been transformed to the setting of Williams et al. (1970) for comparison 









a 


b 


c 


i8 


Locality 


Bariand, unpubl. 






14-17 A 


5-68 


7-13 


ii4°io' 


Iran 


Adib & Ottemann, 


1970 


14-16 


2-84 


7-10 


ii5°3o' 


Anarak, Iran 


Miicke, 1970 






14-032 


5-679 


7-138 


ii5°i6' 


Sierra Gorda, Chile 


Zemann, 1970 






14-00 


5-68 


7-14 


ii5°3o' 


Anarak, Iran 


Williams et al., 1970 




14001 


5-675 


7-137 


Ii5°i3' 


Berezov 


Williams, on BM 393: 


16 


13-993 


5-667 


7-130 


ii5°i6' 


Berezov 


The strongest 


X 


-ray powder diffractions reported 


are : 








Tempi 


e, 1956 


Williams 


Williams 


Williams et al.. 






Leadhills 


BM 39311 


5, 


Harvard 


1970 










Berezov 




6715 1, Berezov Wickenburg 


hkl 


d 


I 


d 


I 


d 


Id I 


001 




6-49 A 


m 


6-437 A 


3\ 


6-389 A 8B /^■43^ 5 


200 




— 


— 


6-318 


3/ 




L6-34 5 


310 




3-38 


vs 


3-383 


10 


3-387 10 


3-380 10 


112, 402, 411 




2-98 


vs 


2-979 


10 


2-981 10 


2-979 10 


020 




2-86 


s 


2-834 


4 


2-836 6 


2-831 5 


202 




2-48 


fs 


2-476 


2 


2-477 5 


2-475 4 


602 




2-26 


fs 


2-264 


4 


2-261 7 


2-263 4 


712, 222, 421 




1-87 


s 


1-868 


5 


1-867 8 B 1-862 5 



4o6 




THE NAT 


URALL 


Y OCCURRING 






Chemistry : 














PbO 
CrOa 


I 
76-69% 
[23-31]* 


2 
79-30 
17-93 


3 
8i-9 
16 


4 5 
81-9 85-67 
i8-3 14-50 


6 

8o-88 
18-08 


7 
81-70 
18-30 



1. Berezov ; Hermann, 1833 

2. Berezov, 'beresovite' ; Samoilow, 1897 ; also COj 2-46% 

3. Iran ; Bariand 

4. Anarak, Iran, 'chrominium' ; Adib & Ottemann, 1970 

5. Sierra Gorda, Chile, 'scheibeite' ; Miicke, 1970 

6. Wickenburg ; Williams et al., 1970 

7. Theory for PbgCrOj 
* By difference. 



Paragenesis. Phoenicochroite is readily distinguished by its deep red colour and 
cleavage. It is the first chromate to form and at Berezov it may occur directly 
upon anglesite, which films galena ; in fact there usually is some fresh galena in 
specimens containing phoenicochroite. Crocoite follows phoenicochroite in the 
paragenesis and, with cerussite, may form fine-grained pseudomorphs after phoeni- 
cochroite. At the Rat Tail claim (Arizona) phoenicochroite occurs as corroded 
blebs in clear, sharply euhedral cerussite crystals, and at the Potter-Cramer (Arizona) 
prospect it occurs in veinlets cutting the host rocks and is partially altered to cerus- 
site stained bright orange by crocoite. 



Vauquelinite, Pb2CuCr04P040H, and fornacite, Pb2(Cu.Fe)Cr04(As,P)040H, 

monoclinic 

Names for vauquelinite include : plomb vert noiratre cuneiforme (Macquart, 
1789) ; chromsaures Kupfer (Karsten, 1808 ; Ullmann, 1814) ; vauquelinite 
(Berzelius, 1818) ; Chromphosphorkupferbleispath (John, 1845) ; Laxmannit 
(Nordenskjold, 1867) ; Phosphorchromit (Hermann, 1870). 

Fornacite (Lacroix, 1915, 1916) has had no synonyms (furnacite was an error). 

Physical properties : Both these minerals are pistachio green to almost black, 
with a dirty yellow streak. H. 2| to 3. Specific gravities range from 5-986 to 
6-12 for vauquelinite (calc. 6-i6 on Williams' cell, 6-22 on Fanfani & Zanazzi's cell) ; 
6-12 to 6-27 for fornacite (6-33 calc. on Cocco et al.'s cell, 6-47 on Bariand & Herpin's 
cell ; both these for the end-member Pb2CuCr04As040H). 

Vauquelinite has 2V^ x 0°, a 2-ii, j8 and y 2-22 (Larsen, 1921 ; Guillemin & 
Prouvost, 1951). Fornacite has 2V near 90°, a 2-14, y 2-24 (Guillemin & Prouvost, 
1951 ; Bariand & Herpin, 1962). 

X-ray data : The space-group for both species is P2ijn ; Z = 4. Cell dimensions 
have been determined by several authors ; in the following table these have been 
converted to Berry's vauquelinite orientation (the morphological setting used by 
Dana (1951) rnay be transformed to Berry's setting by the matrix [30~/oio/ioi]) : 



CHROMATES OF LEAD 



407 





a 




b 


c 


^ 


Locality 




Berry, 1949 
Fanfani & Zanazzi, 1 


13-68 A 
968 13754 




5-83 
5-806 


9-53 
9-563 


93°58' ^ 
94°34' 


1 Vauquelinite, 
1 Ber**"^'*'' 




Williams, on BM 40448 13-726 




5-776 


9-542 


94°55r. 








Bariand & Herpin, i 


962 13-60 




5-91 


9-63 


95°59' 


Sebarz 




Cocco et al., 1966 


13-827 




5-893 


9-694 


94°52' 


Reneville „ 

S HnrnariT^ 


A^i Ilia m c 


/ 13-818 
113-831 




5-870 


9-619 


94°4o' 


Tiger 






VV iilldllLo 




5 899 


9-698 


94°47' 


Congo 


^ 




The strongest X 


-ray powder ( 


diffractions reported 


are : 








Vauquelinite 








Fomacite 






Guillemin & 


Williams on 


Bariand & 




Williams 




Prouvost, 195 1 


BM 40448 




Herpin, 


, 1962 


















Berezov 


Berezov 




Sebarz 


Tiger 




Congo 




d I 


d 


/ 


d 


/ 


d 


/ 


d 


/ 


4-54 A F 


4-696 A 


7 


4-80 A 


9 


4-770 A 


5 


4-812 A 


8 


3-20 F 


3-280 


10 


3-31 


10 


3-311 


10 


3-324 


10 


2-83 F 


2-887 


5 


2-88 


10 


2-913 


6 


2-916 


8 


- 


2-760 


4 


2-80 


10 


2-795 


5 


2-812 


8 


2-70 M 


2-689 


4 


2-71 


9 


2-714 


5 


2-732 


7 


2-26 M 


2-298 


7 


- 


- 


2-324 


4 


2-338 


6 


1-86 F 


1-887 


7 


- 


- 


1-899 


4B 


1-901 


7 


1-82 F 


1-844 


4 


- 


- 


1-858 


3 


1-860 


5 



F = forte, B = broad 

Chemistry : Chemical analyses of these minerals are reported below and have been 
recalculated where necessary, using modern atomic weights. I am very dubious 
of some of these results, particularly on Berezov vauquelinite, since it is very easy 
to obtain mixtures from what appears to be a uniform crust of dark green 'vauque- 
linite'. 





I 


2 






3 






A 


\ 


5 


6 


7 


PbO 


63-44% 6o' 


■87 




50 


■I 




61 


•26 


61-06 


68-33 


62-70 


CuO 


II-20 


10- 


80 




II' 


20 




12 


•43 


10-85 


7-36 


9-58 


CrOa 


14-09 


28- 


33 




21 


•40 




15 


-26 


16-76 


10-13 


11-95 


PaOs 


10-00 


- 






4 


•10 




8 


-05 


8-57 


9-94 


9-23 


Fe.O, 


- 


- 












I 


-09 


1-28 


2-8o 


— 


H2O+ 


1-27 


- 






!■ 


78 




I 


■31 


0-90 


i-i6 


- 


Rem. 


- 


- 






II 


•42 




- 




- 


— 


- 


Lost 


- 


- 












- 




- 


- 


3-00 




8 


9 




10 






II 




12 


13 


14 


15 


PbO 


62-59% 


62-06 




57-7 




63-7 




62-6 


58-3 


57-16 


59-74 


CuO 


12-19 


10-31 




10-2 






8-9 




8-2 


13-27 


10-91 


10-55 


CrOg 


21-46 


17-44 




15-3 




I 


4-4 




15-2 


7-37 


11-78 


13-27 


P2O5 


3-55 


8-66 




0-4 






8-4 




6-8 


- 


0-66 


- 


AS2O5 


- 


- 




13-4 






0-2 




2-6 


20-00 


i5-03t 


15-25 


Fe^O, 


0-70 


0-50 




0-2 






1-7 




1-4 


- 


0-40 


- 


H.,0+ 


- 


- 




1-5 






1-5 




1-5 


2-00* 


2-05 


1-19 


H,0- 


- 


I-I2 




0-9 






0-7 




0-8 


- 


1-68 


- 



* Considered non-essential by the authors who state that the mineral is anhydrous. 
■)■ Misprinted as AsjOj in the original paper. 



408 THE NATURALLY OCCURRING 

1. Vauquelinite ; theory for Pb2CuCr04P040H 

2. Vauquelinite, Berzelius, 1818 

3. Vauquelinite (Chromphosphorkupf erbleispath) , John, 1845 
4 and 5. Vauquelinite (Laxmannite), Nordenskiold, 1867 

6. Vauquelinite (Phosphorchromite) , Hermann, 1870 

7. Vauquelinite, Nicolajew, 1878 

8 and 9. Vauquelinite, Chirva, 1935 
10. Fornacite, Guillemin & Prouvost, 1951 
II and 12. Vauquelinite, Guillemin & Prouvost, 1951 

13. Fornacite, Smol'yaninova & Senderova, 1959 

14. Fornacite, Bariand & Herpin, 1962 

15. Fornacite ; theory for Pb2CuCr04As040H 



Paragenesis : Vauquelinite and fornacite tend to be late-formed oxide-zone 
minerals. They may be perched on and replace earlier crocoite, hemihedrite or 
embreyite, but are just as often transported, and occur in fractures in nearby wall- 
rocks. In some cases, it appears that chromate-bearing solutions derived from dis- 
solution of crocoite have attacked cerussite, and vauquelinite may be perched on and 
in pits in cerussite crystals. 



Embreyite, Pb5(CrO 4) alPOJg.HaO : monoclinic 

Older nomenclature includes : mineral 'theils dunkel ochrebraun, theils dunkel 
leberbraun . . . zeisiggriines Pulver' (Hausmann, 1813) ; 'nelken- und haar-braunes 
Erz . . .' (John, 1845) ; chromo-phosphate de plomb et de cuivre (Pisani, 1880) ; 
possibly also 'oxide jaune ou ocre de plomb' (Macquart, 1789). 

Physical properties : Embreyite is orange or henna in colour with a specific gravity 
of 6-42 (calc. for Cu-free, 6-40). Refractive indices : a 2-20, )8, y 2-36 ; 2Vj^ x 0°. 
^ = [010]. 

X-ray data : Crystals are ill-formed and known only by their X-ray cell : a 
9755 ^> ^ 5'636, c 7-135, /3 i03°5'. Stronger lines of the powder pattern are : 
4751 (6), 3-563 (3). 3-475 (3). 3-167 (10), 2-8i8 (6), 2-608 (2), 2-314 (2), 2-213 (3), 
2-187 (3), 2-105 (3). 1-917 (4)- 

Chemistry : Chemical analyses : 





1 


2 


3 


4 


5 


6 


7 


8 


PbO 


72-25% 


75-30 


74-7 


74-9 


75-0 


74-4 


70-60 


75-61 


CuO 


2-53 


I-20 


1-62 


1-68 


1-45 


1-70 


4-57 


- 


CrOj 


13-08 


- 


13-4 


13-5 


13-5 


13-4 


15-50 


1355 


P2O5 


8-23 


- 


9-57 


9-47 


9-II 


9-09 


9-78 


9-62 


CO., 


I -04 


- 


— 


- 


- 


- 


- 


- 


H2O 


o-gi 


- 


n.d. 


n.d. 


n.d. 


0-91 


— 


1-22 


ZnO 


- 


0-03 


o-o6 


0-02 


o-o6 


0-04 


- 


- 


Fe,0, 


- 


o-oi 


o-oi 


0-04 


001 


0-02 


- 


- 


Sum 


98-04 


- 


99-4 


99-6 


99-2 


99-56 


100-45 


100-00 



I. Schwarzkopf Microanalytical Laboratory, analysts. Cu, Cr, Pb, by atomic absorption on 
3-954 mg ; HjO under Ng at 800 °C on 7-724 mg ; CO2 on 7-725 mg, precipitated as BaCOg. 
P2O5 on 1-582 mg ; COg from cerussite contamination. Ecole des Mines specimen 



CHROMATES OF LEAD 



409 



2. J. A. Allen analyst, all elements by atomic absorption on 5-842 mg. Ecole des Mines specimen 

3, 4, 5. Analyses by electron probe by R. F. Symes and A. M. Clark, British Museum (Natural 

History), on BM 94718 

6. Average of analyses after deducting cerussite from no. i and recalculating to 98-04% 

7. Pisani, 1880 

8. Ph,{CTO,),(PO,)^.U,0 



Iranite and hemihedrite, anorthic 

Nomenclature : Iranite (Bariand & Herpin, 1963) ; khuniite (Adib & Ottemann, 
1970) is clearly identical with iranite. Hemihedrite (Williams & Anthony, 1970), 
is probably isomorphous with iranite. 

Physical properties : Both minerals have a colour between brown and orange, 
with a yellow streak. The specific gravity of iranite has been determined as 5-9 
and 6-1 ; that of hemihedrite is 6-42. The refractive indices are : iranite, a 2-25 
to 2-30, y 2-40 to 2-50 (Bariand & Herpin, 1962) ; hemihedrite, a 2-105, y 2-65 
(Williams & Anthony, 1970). 

X-ray data : Iranite has a io-02 A, b 9-54, c 9-89, a I04°30', j8 66°, y io8°3o' 
(Bariand & Herpin, 1963). Hemihedrite has a 9-497 A, b 11-443, c 10-841, a 120° 
30', /3 92°6', y 55°5o', or, in the same setting as iranite, a 9-95, b 9-50, c 9-91, 
a II0°28', P 66°I0', y I07°58'. 

The strongest X-ray powder diffractions are : 

Iranite 



Bariand & 


Williams 


on 


Adib& 




Hemihedrite^ 
Williams & 


Herpin, 


1963 


type material 


Ottemann, : 


[970 


Anthony, 1970 


d 


/ 


d 


/ 


d 


/ 


d I 


4-84 A 


8 


4-861 A 


7 


4-877 A 


4 


4-872 A 9 


4-42 


8 


4-372 


6 


4-370 


6 


4-364 8 


3-28 


10 


3-282 


10 


3-294 


10 


3-301 10 


3-18 


10 


3-174 


10 


3-185 


9 


3-164 8 


3-08 


10 


3-086 


9 


3-081 


7 


3-102 8 


2-935 


5 


2-917 


4 


2-922 


5 


2-924 5 



Chemistry : The available chemical analyses of both minerals are imperfect : the 
fluorine determination in the hemihedrite analysis is probably high, and so is the 
water determination in the iranite analysis by Hey & Elliott, while Adib & Ottemann 
have not determined water, which is certainly present in iranite. 

Empirical unit-cell contents have been calculated for hemihedrite, taking F by 
difference (F = i-6%) ; the results agree well with the formula ZnPbiolCrOJe 
(5104) 2F2 suggested by the structural work of McLean & Anthony (1970). For 
iranite, empirical unit-cell contents calculated from the mean of analyses 4 and 5, 
taking the specific gravity as 6-0, suggest the formula CuPbio(Cr04)6(OH)io, analogous 
to that of hemihedrite with (OH) 4 replacing Si04. 



4IO THE NATURALLY OCCURRING 





I 


2 


3 


4 


5 


6 


7 




8 


CuO 


0-04 


- 


- 


2-6 


4-1 


3-4 


2-65 


Cu 


o-oi 


ZnO 


2-85* 


2-66 


- 


2-5 


2-3 


I -4! 


- 


Zn 


i-i 


PbO 


7274 


73-05 


66-2 


74-0 


72-3 


73-1 


74-36 


Pb 


9-9 


Cr03 


20-14 


19-64 


28-8 


2I-0 


15-9 


i8-5 


19-99 


Cr 


6-1 


SiOj 


3-31 


3-93 


- 


- 


- 


- 


- 


Si 


1-7 


HP 


- 


- 


+ 


- 


8-1 


3-6J 


3-00 





31-4 


F 


5-27 


1-24 


- 


- 


- 


- 


- 


OH 


- 




104-35 


100-52 


95-0 


lOO-I 


102-7 


loo-o 


100-00 


F 


2-6 


Less Oe 


=F 2-21 


0-52 


















I02-I. 


1 lOO-OO 
















■34-0 ii-» ^33-5 



* Mean of 3-93, 2-14 and 2-49. 
t Mean of 2-5, 2-3, 0-20 and 0-43. 
j By difference. 

1. Hemihedrite, Williams & Anthony, 1970, with additional Zn determinations by Williams 
A specimen from Boulder City gave CuO 0-58%, ZnO 1-30 

2. Hemihedrite, calculated for ZnPbi(,(Cr04)6(Si04)2F2. Sp. gr. calc. 6-44 (obs. 6-42) 

3. Iranite ; Bariand & Herpin, 1963 

4. Iranite ('khunite') ; Adib & Ottemann, 1970 

5. Iranite ; Hey & Elliott (unpubl.) on 230 /xg of type material ; colorimetric and atomic 
absorption analysis 

6. Mean of 4 and 5, with additional Zn and Cu determinations by Williams 

7. Iranite, calculated for CuPbio(Cr04)e(OH)io. Sp. gr. calc. 6-14 (obs., 5-9, 6-1) 

8. Hemihedrite. Empirical unit cell contents (see text) 

9. Iranite. Empirical unit cell contents (see text) 

Paragenesis : Iranite and hemihedrite form in the oxide zone at low Eh and 
probably in neutral to slightly alkaline waters. They may be expected to form after 
phoenicochroite and anglesite and earlier than vauquelinite or embreyite. Crocoite 
and hemihedrite appear roughly contemporaneous at the Potter-Cramer mine. 

Santanaite, hexagonal 

Crystals are tabular yellow hexagonal and exhibit a good basal cleavage. Indices 
of refraction are a> = 2-32, £ = 2-12. 

Stronger powder pattern lines are : 3-539 (10), 2-606 (8), 2-080 (5), 1-701 (5), 
2-948 (4), 2-846 (4), 2-243 (4)- 

Electron probe analysis gave Pb 88-0 ± 2-0%, Cr 1-9 ± 0-2, oxygen by difference, 
leading to PbiiCr0^g_(_3). 



SELECT BIBLIOGRAPHY 

Adib, D. & Ottemann, J. 1970. Some new lead oxide minerals and murdochite from T. 

Khuni mine, Anarak, Iran. Miner. Deposita, 5 : 86-93. 

■ & NuBAR, B. 1972. Neues Jb. Miner. Mh. : 328-335. 

Alford, C. J. 1894. On auriferous rocks from Mashonaland. Proc. Geol. Soc. Land. 50 : 8-9. 
Anderson, C. 1906. Mineralogical notes : No. m - axinite, petterdite, crocoite and datolite. 

Rec. Austr. Mus. 6 : 133-145. 



CHROMATES OF LEAD 411 

Arndt, H., Reis, O. & ScHWAGER, A. 1918/1919. tJbersicht der Mineralien und Gesteine der 

Rheinpfalz, Geol. Jber. 31/32 : 119-262. 
Arzruni, a. 1885. Untersuchungen einiger granitischer Gesteine des Urals. Z. dt. geol. Ges. 

37 : 865-896. 
A. V. A. 1 801. Berichtigung der Untersuchung des rothen Sibirischen Bleispaths von Sage 

(Annalen 5, B. 62) durch Gegenversuche von Thenard. Annln Phys. 8 : 237-239. 
Badams, J. 1825. On a scarlet sub-chromate of lead, and its application to painting and 

calico-printing. Ann. Phil. 25 : 303-305. 
Baerwald, C. 1882. Analyse und Brechungsexponenten des Rothbleierzes von Berjow- 

sowsk. Z. Kristallogr. Miner. 7 : 170- 171. 
Bariand, p. 1963. Contribution a la mineralogie de I'lran. Bull. Soc.fr. Miner. Cristallogr. 

86 : 17-64. 
& Herpin, p. 1962. Nouvelles donnees sur la fornacite (chromo-arseniate de plomb et 

de cuivre). Bull. Soc.fr. Minir. Cristallogr. 85 : 309-311. 
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